CENSUS OF POPULATION AND HOUSING, 1990 [UNITED STATES]: PUBLIC USE MICRODATA SAMPLE: 1/10,000 SAMPLE (ICPSR 6150) Principal Investigators United States Department of Commerce Bureau of the Census and Inter-university Consortium for Political and Social Research First ICPSR Release August 1993 Inter-university Consortium for Political and Social Research P.O. Box 1248 Ann Arbor, Michigan 48106 1 1 BIBLIOGRAPHIC CITATION Publications based on ICPSR data collections should acknowledge those sources by means of bibliographic citations. To ensure that such source attributions are captured for social science bibliographic utilities, citations must appear in footnotes or in the reference section of publications. The bibliographic citation for this data collection is: U.S. Dept. of Commerce, Bureau of the Census, and Inter-university Consortium for Political and Social Research. CENSUS OF POPULATION AND HOUSING, 1990 [UNITED STATES]: PUBLIC USE MICRODATA SAMPLE: 1/10,000 SAMPLE [Computer file]. Washington, DC: U.S. Dept. of Commerce, Bureau of the Census [producer], 1992. Ann Arbor, MI: Inter-university Consortium for Political and Social Research [distributor], 1993. REQUEST FOR INFORMATION ON USE OF ICPSR RESOURCES To provide funding agencies with essential information about use of archival resources and to facilitate the exchange of information about ICPSR participants' research activities, users of ICPSR data are requested to send to ICPSR bibliographic citations for each completed manuscript or thesis abstract. Please indicate in a cover letter which data were used. DATA DISCLAIMER The original collector of the data, ICPSR, and the relevant funding agency bear no responsibility for uses of this collection or for interpretations or inferences based upon such uses. 1 1 DATA COLLECTION DESCRIPTION United States Department of Commerce. Bureau of the Census, and Inter-university Consortium for Political and Social Research CENSUS OF POPULATION AND HOUSING, 1990 [UNITED STATES]: PUBLIC USE MICRODATA SAMPLE: 1/10,000 SAMPLE (ICPSR 6150) SUMMARY: This dataset, prepared by the Inter-university Consortium for Political and Social Research, comprises 1 percent of the cases in the second release of CENSUS OF POPULATION AND HOUSING, 1990 [UNITED STATES]: PUBLIC USE MICRODATA SAMPLE: 1-PERCENT SAMPLE (ICPSR 9951). As 1 percent of the 1-Percent PUMS, the file constitutes a 1-in-10,000 sample, and contains all housing and population variables in the original 1-Percent PUMS. Housing variables include area type, state and area of residence, farm/nonfarm status, type of structure, year structure was built, vacancy and boarded-up status, number of rooms and bedrooms, presence or absence of a telephone, presence or absence of complete kitchen and plumbing facilities, type of sewage, water source and heating fuel used, property value, tenure, year moved into house/apartment, type of household/family, type of group quarters, language spoken in household, number of persons, related children, own/adopted children, and stepchildren in the household, number of persons and workers in the family, status of mortgage, second mortgage, and home equity loan, number of vehicles available, household income, sales of agricultural products, payments for rent, mortgage, and property tax, condominium fees, mobile home costs, and costs for electricity, water, heating fuel, and flood/fire/hazard insurance. Person variables cover age, sex, relationship to householder, educational attainment, school enrollment, race, Hispanic origin, ancestry, language spoken at home, citizenship, place of birth, year of immigration, place of residence in 1985, marital status, number of children ever born, presence and age of own children, military service, mobility and personal care limitations, work limitation status, employment status, employment status of parents, occupation, industry, and class of worker, hours worked last week, weeks worked in 1989, usual hours worked per week, temporary absences from work, place of work, time of departure for work, travel time to work, means of transportation to work, number of occupants in vehicle during ride to work, total earnings, total income, wages, and salary income, farm and nonfarm self-employment income, Social Security income, public assistance income, retirement income, and rent, dividend, and net rental income. CLASS III UNIVERSE: All persons and housing units in the United States. SAMPLING: The 1-in-10,000 sample, extracted from the 1-Percent PUMS by ICPSR using a systematic selection procedure, contains all housing records in the 1-Percent PUMS coded 16 for the subsample 1 variable, SUBSAMPL, plus all person records associated with these housing records. The number 16 was randomly chosen among the 100 possible codes for SUBSAMPL, 00 to 99. (See chapter 4 of the codebook for an explanation of how SUBSAMPL may be used to select PUMS subsamples.) The 1-Percent PUMS, derived from responses to the 1990 Census long-form questionnaire, is a 1-percent stratified sample of persons and housing units enumerated in the 1990 Census (housing units and their occupants, vacant housing units, and persons in group quarters). The long-form questionnaire was administered to approximately 15.9 percent of households counted by the Census. NOTE: (1) To approximate weighted frequencies given by the original 1-Percent PUMS, users should multiply the weight variables, HOUSWGT and PWGT1, by 100. (2) This dataset has the same hierarchical structure as the original 1-Percent PUMS. There is a separate record type for each of the two levels in the hierarchy: the housing level is represented by a housing record comprising 112 housing variables, the person level by a person record comprising 123 person variables. (These variable counts do not include the housing serial number, SERIALNO, and the variable denoting the record type, RECTYPE. These two variables appear on both the housing and person records.) Each occupied housing unit is represented by a single housing record followed by one or more person records, one for each person in the household. Housing records representing vacant housing units are not followed by any person records. Each person residing in group quarters is represented by a housing record followed by a person record. In all, this dataset contains 36,179 records: 11,074 housing records and 25,105 person records. Every housing and person record has a logical record length of 231. (3) Appendix G of the codebook (PUMS maps) is available only in hard copy form upon request from ICPSR. (4) Code 5, which denotes this 1/10,000 sample, has been added to the variable SAMPLE. EXTENT OF COLLECTION: 1 data file + machine-readable documentation (text) + database dictionary + SAS Control Cards + SPSS Control Cards EXTENT OF PROCESSING: MDATA/ NONNUM DATA FORMAT: Logical Record Length with SAS and SPSS Control Cards Part 1: Data File Part 2: SAS Control Cards File Structure: hierarchical Record Length: 80 Record Length: 231 Part 3: Data Dictionary Part 4: Geographic Equivalency File Record Length: 80 Record Length: 80 1 CONTENTS Page Abstract------------------------------------------------------ 3 Introduction-------------------------------------------------- 11 How to Use This File------------------------------------------ 19 Accuracy of the Microdata Sample Estimates-------------------- 29 Sample Design and Estimation---------------------------------- 57 Record Contents----------------------------------------------- 71 Indexes to Variables------------------------ 71 Data Dictionary----------------------------- 85 User Notes---------------------------------------------------- 127 APPENDIXES A. Area Classifications-------------------------------------- 137 B. Definitions of Subject Characteristics-------------------- 165 C. Notes on Selected Data Items------------------------------ 273 D. Collection and Processing Procedures---------------------- 295 E. Facsimiles of Respondent Instructions and Questionnaire Pages--------------------------------------------------- 305 F. Data Products and User Assistance------------------------- 307 G. Maps (will be released as user notes)--------------------- 335 H. Record Layout of Machine-Readable Data Dictionary--------- 351 I. Code Lists------------------------------------------------ 353 ICPSR Note: User Notes have been added to this second edition of the codebook, beginning on page 127. 1 Page 2 ICPSR 6150 - 1 ICPSR 6150 Page 3 ABSTRACT Page Citation------------------------------------------------------ 3 File Availability--------------------------------------------- 7 Geographic Coverage------------------------------------------- 4 Related Electronic Media Products----------------------------- 7 Related Printed Reports--------------------------------------- 5 Related Reference Materials----------------------------------- 8 Software Considerations--------------------------------------- 8 Subject Matter Description------------------------------------ 3 Technical Description----------------------------------------- 8 Type of File-------------------------------------------------- 3 Universe Description------------------------------------------ 3 CITATION Census of Population and Housing, 1990: Public Use Microdata Samples (machine-readable data files) / prepared by the Bureau of the Census. -Washington: The Bureau (producer and distributor), 1992. TYPE OF FILE Microdata UNIVERSE DESCRIPTION All persons and housing units in the United States. SUBJECT MATTER DESCRIPTION Public Use Microdata Samples (PUMS) contain records representing 5% or 1% samples of the housing units in the U.S. and the persons in them. Selected group quarters persons are also included. The file contains individual weights for each person and housing unit which, when applied to the individual records, expand the sample to the total population. Most population and housing items are listed below. Please see the Data Dictionary for a complete listing of variables and recodes. Both the 5% and 1% samples have the same subject content and vary only in geographic composition of the Public Use Microdata Area (PUMA). A 3% elderly sample will be available later. 1 Page 4 ICPSR 6150 Items on the housing record include: Allocation Flags for Housing Mortgage Status and Selected Items Monthly Owner Costs Bedrooms Plumbing Facilities Condominium Status Presence and Age of Own Contract Rent Children Cost of Utilities Presence of Subfamilies Family Income in 1989 Family, in Household Subfamily and Relationship Property Value Recodes Real Estate Taxes Farm Status and Value Rooms Fire, Hazard, Flood Insurance Sewage Disposal Fuels Used Source of Water Gross Rent State (Residence) House Heating Fuel Telephone in Housing Unit Household Income in 1989 Tenure Household Type Units in Structure Housing Unit Weight Vacancy Status Kitchen Facilities Vehicles Available Linguistic Isolation Year Householder Moved into Unit Meals Included in Rent Year Structure Built Items on the person record include: Ability to Speak English Mobility Status Age Occupation Allocation Flags for Population Person's Weight Items Personal Care Limitation Ancestry Place of Birth Children Ever Born Place of Work PUMA Citizenship Place of Work State Class of Worker Poverty Status in 1989 Disability Status Race Educational Attainment Relationship Hispanic Origin School Enrollment and Type Hours Worked of School Income in 1989 by Type Time of Departure for Work Industry Travel Time to Work Language Spoken at Home Vehicle Occupancy Marital Status Weeks Worked in 1989 Means of Transportation Work Status in 1989 Migration PUMA Work Limitation Status Migration State Year of Entry Military Status, Periods of Active Duty Military Service, Veteran Period of Service GEOGRAPHIC COVERAGE 1 ICPSR 6150 Page 5 Each PUMS file provides records for States and many of their geographic levels. The hierarchy is shown below: The 5% sample identifies every State and various subdivisions of States called "Public Use Microdata Areas", each with at least 100,000 persons. These PUMAs were primarily based on counties, and may be whole counties, groups of counties, and places. When these entities have more than 200,000 persons, PUMAs can represent parts of counties, places, etc. None of these PUMAs on the 5% sample crosses state lines. On the other hand, the 1% sample was based primarily on metropolitan/nonmetropolitan areas, and contains PUMAs which were made from whole central cities, whole MSAs or PMSAs, MSA or PMSAs outside the central city, groups of MSAs or PMSAs, and groups of areas outside MSAs or PMSAs. When the areas have more than 200,000 persons, 1% PUMAs can represent parts of central cities, MSA/PMSAs, and so forth. 1% PUMAs may cross State lines and in that case State codes are not shown. See examples of PUMAs in figures 2-4. RELATED PRINTED REPORTS Since individual weights are provided on PUMS, most estimates derived from PUMS tabulations can be checked for reasonableness against other 1990 printed reports, STF's or microfiche produced from sample data. Listed below are the 1990 census printed reports containing sample data from summary tape products STF 3 and STF 4 which may be used to verify estimates provided from PUMS files. These reports will be available from Superintendent of Documents, U.S. Government Printing Office, Washington, DC 20402. An order form follows this abstract. 1990 CPH-3, Population and Housing Characteristics for Census Tracts and Block Numbering Areas. One report will be published for each metropolitan area (MA) and one for the non-metropolitan balance of each State, Puerto Rico and the U.S. Virgin Islands showing data for most of the population and housing subjects included in the 1990 census. Some tables will be based on the 100-percent tabulations, others on the sample tabulations. (Scheduled for release in 1992-93.) 1990 CPH-4, Population and Housing Characteristics for Congressional Districts of the 103rd Congress. A report for each State and the District of Columbia which provides both 100-percent and sample data for States, congressional districts, and, within congressional districts, counties, places of 10,000 or more inhabitants, county subdivisions of 10,000 or more inhabitants in 12 States, and American Indian and Alaska Native areas. (Scheduled for release in 1994.) 1 Page 6 ICPSR 6150 1990 CPH-5, Summary Social, Economic, and Housing Characteristics. These reports, issued for the United States, States, District of Columbia, Puerto Rico and the U.S. Virgin Islands, provide sample population and housing data for states and local government units, (i.e., counties, places, towns, and townships) other county subdivisions and American Indian and Alaska Native areas. 1990 CP-2, Social and Economic Characteristics. These reports are issued for the United States, States, District of Columbia, Puerto Rico, and the U.S. Virgin Islands. They focus on the population subjects collected on a sample basis in 1990. Data are shown for States (including summaries such as urban and rural), counties, places of 2,500 or more inhabitants, county subdivisions of 2,500 or more inhabitants in selected States, and the State portions of American Indian and Alaska Native areas. (Scheduled for release in 1993.) 1990 CP-2-1A, Social and Economic Characteristics for American Indian and Alaska Native Areas. Data are shown for American Indian and Alaska Native areas. (Scheduled for release in 1993.) 1990 CP-2-1B, Social and Economic Characteristics for Metropolitan Areas. Data are shown for MA's. (Scheduled for release in 1993.) 1990 CP-2-1C, Social and Economic Characteristics for Urbanized Areas. Data are shown for UAs. 1990 CP-3, Population Subject Reports. Thirty reports are planned covering populations subjects and subgroups. These include migration, income, and the older population. Geographic areas generally will include the United States, regions, and divisions; some reports may include data for highly populated area such as States, MA's, counties and large places. Scheduled for release in 1993. 1990 CH-2, Detailed Housing Characteristics. These reports, issued for the United States, States, District of Columbia, Puerto Rico, and the U.S. Virgin Islands focus on the housing subjects collected on a sample basis in 1990. Data are shown for State (including summaries such as urban and rural), counties, places of 2,500 or more inhabitants, MCD's of 2,500 or more inhabitants in selected States, Alaska Native areas and the State portion of American Indian areas. (Scheduled for release in 1993.) 1990 CH-2-1A, Detailed Housing Characteristics for American Indian and Alaska Native Areas. Data are shown for American Indian and Alaska Native areas. (Scheduled for release in 1993.) 1990 CH-2-1B, Detailed Housing Characteristics for 1 ICPSR 6150 Page 7 Metropolitan Areas. Data are shown for MA's. (Scheduled for release in 1993.) 1990 CH-2-1C, Detailed Housing Characteristics for Urbanized Areas. Data are shown for UA's. (Scheduled for release in 1993.) 1990 CH-3, Housing Subject Reports. Ten Housing subject reports are planned covering 1990 census items such as structural characteristics and space utilization. Geographic areas generally include the United States, regions, and divisions; some reports may include data for other highly populated geographic areas such as States, MA's, counties, and large places. (Scheduled for release in 1993.) RELATED ELECTRONIC MEDIA PRODUCTS PUMS data on compact disk-read only memory (CD-ROM) are issued after the all tape files are released. CENDATA, the Census Bureau's online system, carries PUMS Technical Documentation. STF 3 data are available also on CD-ROM and magnetic tape. Contact Customer Services (301-763-4100) for additional information on electronic media products. FILE AVAILABILITY PUMS files are provided for each State and the District of Columbia and are released on a State-by-State basis. All files and pricing information are available from Customer Services, Data User Services Division, Bureau of the Census, Washington, DC 20233. (See above for phone and FAX information.) A machine-readable data dictionary is included on the tape without charge. Options include 6250 or 1600 bpi, ASCII or EBCDIC, labeled or unlabeled. The files are also available on tape cartridges (IBM3480 or compatible format) for the same price. When ordering, please use the order form at the end of this Chapter. Files for the individual States are priced according to the number of megabytes of data they contain; each megabyte is priced at $1.25 regardless of the tape specifications. The minimum charge for a computer tape is $175 for one or more files. See the enclosed order blank for prices of the various PUMS files. Although a user can order a single file, we have packaged the files by census division for sale since many users order all of the states or at least states which border their state. Discount prices are available where all files in a group are paid for at the time of ordering. See order blank for specific prices. 1 Page 8 ICPSR 6150 RELATED REFERENCE MATERIALS 1990 Census Population and Housing Tabulation and Publication Program. This booklet provides descriptions of the data products available from the 1990 census. Available without charge from Customer Services (see above). Census '90 Basics. This booklet provides a general overview of census activities and detailed information on census content, geographic areas, and products. Available without charge from Customer Services (see above). Census ABC's-Applications in Business and Community. This booklet highlights key information about the 1990 census and illustrates a variety of ways the data can be used. Available without charge from Customer Services (see above). A comprehensive 1990 Census of Population and Housing Guide will be available in 1990. It will provide detailed information about all aspects of the census and a comprehensive glossary of census terms. TECHNICAL DESCRIPTION The file contains two record types a "housing" record and a "person" record each consisting of 231 characters of data. Each housing unit record is followed by a variable number of persons records, one for each occupant. Vacant housing units will have no person record, and selected persons in group quarters will have a dummy housing record and a person record. The 5% (A) sample includes a separate file for each state. The 1% (B) sample includes a file for each State and a file containing PUMAs which cross State lines. The 3% (O) sample (elderly file) has the same geographic composition as the 5% sample, (but includes housing units with at least one person age 60 and over or group quarters persons age 60 and over.) The block size for the files varies with each user's specifications, however the standard block size is 32,340 characters for 1990 PUMS. SOFTWARE CONSIDERATIONS The 1990 Public Use microdata files are a special type of nonrectangular file-hierarchical. That is, the file contains several record types each with different variables, rather than one gigantic record with all the variables. We release the PUMS in this format because of the tremendous amount of data contained in one record. 1 ICPSR 6150 Page 9 The file is sorted to maintain the relationship between both record types. Although these records are extremely large they can be handled by most statistical or report writing software. There are two basic record types: the housing unit record and the person record. For 1990, each of the records contains a serial number which links the persons in the housing unit to the proper housing unit record, so that a user no longer needs to worry about keeping the record sequence as the file was delivered. In today's information processing environment, most standard statistical software packages are now capable of handling the file in either format: hierarchical or rectangular structure. Most software packages, such as SAS, SPSS, BMDP, and some relational data base systems, will in fact rectangularize hierarchical files. Further, the manuals accompanying most packages contain samples of code showing how to process the files. Several of the packages also have extract procedures already coded into the software. The 1990 PUMS will be accompanied by electronic data dictionaries in a format which will allow the user to read in ASCII characters and prepare statements transforming the variables and their corresponding descriptions and values to the proper statements required by the software package of choice. The files will be ASCII, with no special software appended, so as to be compatible with most software packages. But the technical documentation will include a section on "how to use this file", where software concerns will be addressed. The user must be familiar with the processing system's limitations and the efficiency of the procedures within the software packages. Users may also write their own code enabling them to perform custom tabulations on their system of choice. 1 Page 10 ICPSR 6150 - 1 ICPSR 6150 Page 11 CHAPTER 1. INTRODUCTION OVERVIEW Public-use microdata samples are computer accessible files which contain records for a sample of housing units, with information on the characteristics of each unit and the people in it. We exclude information which would identify a household or an individual in order to protect the confidentiality of respondents. Within the limits of the sample size and geographic detail, these files allow users to prepare virtually any tabulations they require. Separate public-use microdata samples are available, each representing five percent or one percent of the population and housing of the United States: o 5% Sample, identifying all States and various subdivisions within them, including most counties with 100,000 or more inhabitants; o 1% Sample, identifying all metropolitan territory and most MAs with 100,000 or more inhabitants individually, and groups of (MAs) elsewhere; A 3% elderly sample will be available also. WHAT IS MICRODATA? We provide computer accessible data products in several formats as summary data or as microdata. Summary data are the type of data found in census printed reports, summary tape files, microfiche, and most special tabulations; microdata are the information collected from each person and housing unit on the questionnaire. In summary data, the basic unit of analysis is a specific geographic area (for example, a census tract, county or State) for which counts of persons or housing units (or aggregated data) in particular categories are provided. In microdata, the basic unit is an individual housing unit and the persons who live in it. Figure 1 illustrates the basic distinctions between summary data and microdata. Often, there are two types of microdata: Confidential microdata include the census basic record types, computerized versions of the questionnaires collected from households, as coded and edited during census processing. The Census Bureau tabulates these confidential microdata in order to produce the summary data that go into the various reports, summary tape files (STFs), and special tabulations. Public-use microdata samples are extracts from the confidential 1 Page 12 ICPSR 6150 microdata taken in a manner that avoids disclosure of information about identifiable households or individuals. PROTECTING CONFIDENTIAL INFORMATION All data released (in print or electronic media) by the Bureau of the Census are subject to strict confidentiality measures imposed by the legislation under which our data are collected: Title 13, U.S. Codes which protects the confidentiality of individual respondents. Responses to the questionnaire can be used only for statistical purposes, and Census Bureau employees are sworn to protect respondents' identities. Records on public-use microdata samples are selected after the confidentiality edit is performed, and contain no names or addresses. Also, the Bureau limits the detail (topcodes, recodes) on place of residence, place of work, high incomes, and other selected items to further protect the confidentiality of the records. Microdata records identify no geographic area with fewer than 100,000 inhabitants. Microdata samples include only a small fraction of the population, drastically limiting the chance that the record of a given individual is even contained in a public-use microdata file, much less identifiable. USES OF MICRODATA FILES Public-use microdata files essentially make possible "do-it-yourself" special tabulations. Since the 1990 files furnish nearly all of the detail recorded on long-form questionnaires in the census, subject to the limitations of sample size and geographic identification, users can construct an infinite variety of tabulations interrelating any desired set of variables. Users have the same freedom to manipulate the data that they would have if they had collected the data in their own sample survey, yet these files offer the precision of census data collection techniques and sample sizes larger than would be feasible in most independent sample surveys. Microdata samples will be useful to users (1) who are doing research that does not require the identification of specific small geographic areas or detailed cross tabulations for small populations, and (2) who have access to programming and computer time needed to process the samples. Microdata users frequently study relationships among census variables not shown in existing census tabulations, or concentrate on the characteristics of certain specially defined populations, such as unemployed homeowners or families with four or more children. 1 ICPSR 6150 Page 13 SAMPLE DESIGN AND SIZE Each microdata file is a stratified sample of the population, actually a subsample of the full census sample (approximately 15.9% of all housing units) that received census long-form questionnaires. Sampling was done housing unit-by-housing unit in order to allow study of family relationships and housing unit characteristics. Sampling of persons in institutions and other group quarters was done on a person-by-person basis. Vacant units were sampled also. There are two independently drawn samples, designated "5% (A)" and "1% (B),", each featuring a different geographic scheme, as discussed below. Samples from the 1970 and 1960 censuses also employed a 1% sample size, the 5% sample was new for 1980. Nationwide, the 1990 5% Sample gives the user records for over 12 million persons and over 5 million housing units. On the other hand, since processing a smaller sample is less expensive, some users will want to produce extracts using the subsample numbers provided in the housing record. Sample design is discussed more thoroughly in chapter 4. Unlike 1980, each file contains individual weights for both the housing unit and the persons in the unit. The user can estimate the frequency of a particular characteristic for the entire population by summing the weight variables for records with that characteristic from the microdata file. A section of Chapter 4 discusses the preparation and verification of estimates (see page 4-1). Reliability improves with increases in sample size, so the choice of sample size must represent a balance between the level of precision desired and the resources available for working with microdata files. By using tables provided in chapter 3 (see page 3-2), one can estimate the degree to which sampling error will affect any specific estimate prepared from a microdata file of a particular sample size. Many factors affect the user's decision on which file to use. Users of microdata files for State or MSA estimates would normally use a 1% or 5% sample, while users concerned only with national figures can frequently get by with a smaller sample, say a 0.1-percent (one-in-a-thousand) sample. Although we no longer provide the 0.1% file we do provide subsample numbers which allow scientifically designed extracts of various sizes to be drawn. Even national users may need a 1% or a 5% sample if extremely detailed tabulations are needed, or if users are concerned with very small segments of the population, for example, females 75 years old or over of Italian ancestry. One of the examples in chapter 3 discusses the selection of the appropriate sample size for a particular study. SUBJECT CONTENT 1 Page 14 ICPSR 6150 Microdata files contain the full range of population and housing information collected in the 1990 census: 500 occupation categories, age by single years up to 90, wages in dollars up to $140,000, and so forth. Because the samples provide data for all persons living in a sampled household, users can study how characteristics of household members are interrelated (for example, income and educational attainment of husbands and wives). Information for each housing unit in the sample appears on a 231-character record with geographic and housing items, followed by a variable number of 231-character records with person's information, one record for each member of the household. Items on the housing record are listed beginning on page 5-1; items on the persons record are listed beginning on page 5-4. Although each of the items as collected is further defined in the glossary (reprinted from the 1990 Census Users' Guide) presented as appendix B to this document, it is important to note that we modified several items on the microdata file to provide protection for individual respondents. We also include many transformed variables (recodes), such as those appearing on the STF 3A files, so that users can analyze many complex relationships between records. Data users will frequently want to generate additional variables or develop recodes to meet their individual needs. While it is impossible to predict all the transformations (recodes) required by data users, we included many of the more common ones (household income, selected monthly owner costs, poverty status, and so forth). Transformations such as these, as well as corrections that apply to certain subjects, are discussed in appendix C. We edited the sample questionnaires for completeness and consistency, and made substitutions or allocations for any missing data. Allocation flags appear at the end of each record indicating each item which has been allocated. Thus, a user desiring to tabulate only actually observed values can eliminate variables with allocated values. Editing and allocation flags are discussed beginning on page 3-15. 1 ICPSR 6150 Page 15 Figure 1. Comparison of Summary Data With Information on Microdata Files SUMMARY DATA o Basic unit is an identified geographic area o Data summarized on people and housing in areas o Available for small areas Illustrative Summary Data City Total Occupied Number Renter Gross Rent Pop Housing Persons Occupied Under $100- $150- Units Per Unit Units $100 149 199 Weston City 110,938 49,426 2.2 31,447 158 3,967 13,282 Smithville 21,970 7,261 3.1 2,492 37 190 1,766 Junction 17,152 5,494 2.7 822 11 29 238 PUBLIC-USE MICRODATA o Basic unit is an unidentified housing unit and its occupants o Unaggregated data to be summarized by the user o Allows detailed study of relationships among characteristics o Not available for small areas Illustrative Microdata* ---------------------------------------------------------------------- Housing Housing Housing unit #1 unit #2 unit #3 State of Residence Virginia Virginia Virginia PUMA Area name Area name Area name or code or code or code Persons in household 3 1 0 Telephone Yes Yes N/A Complete plumbing Yes Yes Yes Monthly rent $525-549 $650-699 $300-324 Vehicles 2 1 N/A Household type Married-couple Nonfamily Vacant family householder 1 Page 16 ICPSR 6150 Persons: 1a 1b 1c 2a Housing unit no. 1 1 1 2 Relationship Householder Spouse Child Householder Sex M F M F Age 37 35 6 62 Race W W W B Place of Birth Kansas Virginia Virginia Alabama Occupation Plumber NA NA Postsecondary economics teacher Earnings $28,100 0 0 $45,300 ---------------------------------------------------------------------- * Public-use microdata samples do not actually contain alphabetic information. Such information is converted to numeric codes; for example, the State of Virginia has a numeric code of 51. GEOGRAPHIC IDENTIFICATION The 5% and 1% Samples each feature a different geographic scheme: We call the geographic areas PUMAs for Public Use Microdata Areas. We use the term to apply to each of the areas identified on these files. A 5-digit number, unique within State, identifies each PUMA. The first three digits is the PUMA code and the last two are the sub-PUMA. The sub-PUMA is used when counties or metropolitan areas are subdivided by groupings of census tracts. For example, the PUMAs for Bronx County, New York consist of several groups of census tracts numbered from 05101 through 05111, whereas the PUMA numbered 03500 is made up of 3 counties: Courtland, Tioga and Tompkins Co. The State Data Center provided the PUMAs for most states. For the states of Georgia, Indiana, and Oregon, the Census Bureau developed the PUMAs with input from the respective State Data Center. o The 5% Sample identifies every State, most individual counties or county equivalents with 100,000 or more inhabitants, many individual cities or groups of places with 100,000 or more inhabitants, and for counties with at least 200,000 inhabitants groupings of Census tracts are also identified. Areas with populations under 100,000 have been grouped into reasonable analytic units often equivalent to State planning district boundaries. In New England, areas are defined in terms of cities and towns rather than counties. 1 ICPSR 6150 Page 17 The 1% Sample identifies MAs of 100,000 or more inhabitants. The remaining MAs are paired together so that metropolitan and nonmetropolitan territory can be separately analyzed. Many large cities, groups of cities, and counties are identified within large MAs. Outside MAs, counties are grouped according to State planning districts or into other reasonable analytic units with populations of 100,000 or more. On the 1% sample, when PUMAs cross state boundaries, states are not separately identified. All of these records appear on a separate file where the state is identified as "99". (See Appendix G). The characteristics of the different geographic schemes are compared in the maps and charts which follow in figures 2, 3, and 4. Purchasers of the 1% Sample for any of the States which include area in a county group crossing State lines may want to request that the "State Code 99" file be stacked onto a tape being purchased. Estimates of the number of tapes required for specified groups of files at a given density and blocking factor are available on request from Customer Services. At the time of this printing, we have not produced files for all States, and estimates of the number of tapes required for specified groups of files at a given density and blocking factor are available on request from Customer Services. We will issue a user note updating this information when all files are produced. CORRESPONDING MICRODATA FROM EARLIER CENSUSES PUMS files exist for the 1960, 1970 and 1980 censuses. Very little comparability exists between geographic identifiers on each of the previous files, but housing and population characteristics are similar. And because of this similarity, microdata files from the most recent censuses are a rich resource for analysis of trends. Items which were added, dropped, or substantially changed between 1980 and 1990 are listed in figure 5. Appendix B discusses historical comparability of items in greater detail. 1 Page 18 ICPSR 6150 - 1 ICPSR 6150 Page 19 CHAPTER 2. HOW TO USE THIS FILE This chapter serves as a guide for data users to both the tape and the technical documentation. Novice users trying to understand how to use the documentation and the file should read this chapter first. DOCUMENTATION CHAPTERS The Abstract chapter in this documentation provides a quick overview of the file, including the formal title, geographic coverage, subject coverage, and file availability. Also shown are citations for related reference materials and printed reports. Their titles and geography are included in this section, along with purchasing information. Chapter 1 describes microdata, chapter 3 describes accuracy of the data, and chapter 4 describes the sample design and estimation for PUMS. USER NOTES Information about file or documentation changes sometimes becomes available after the documentation has been printed. User notes inform the user community about these changes. These are issued in a numbered series. If there are technical documentation changes, revised pages usually accompany them. The revised pages should be inserted in their proper location, but the user note cover sheet should be filed in the User Notes chapter. Technical notes, which contain file errata, are also issued by the Census Bureau. We suggest filing these following appendix I. DATA DICTIONARY The data dictionary (code book) describes the file and provides character locations for each variable. The components include a short mnemonic or field name for use with software packages; field size; starting position; and a description of field contents with possible values. There also is a machine-readable data dictionary file on the data tape. This dictionary is designed to be converted for use with various software packages. APPENDIXES 1 Page 20 ICPSR 6150 Detailed information on geographic areas is in appendix A followed by subject-matter definitions in appendix B. Appendix C provides information about the data changes on PUMS while appendix D outlines the data collection and processing procedures. Facsimiles of both the respondent instructions and 1990 census long-form questionnaire are in appendix E. Appendix F furnishes detailed information on all the data products of the 1990 census, as well as suggested sources of information and assistance. Map information is included in appendix G (to be supplied as user notes). The record layout for the machine-readable data dictionary file that accompanies each tape order is in appendix H. Appendix I contains the code lists used in processing the data for most sample products. These are especially helpful in determining the components included in categories such as race, and group quarters. On the PUMS, the information on these lists may be changed for disclosure protection purposes. Those changes are indicated in the data dictionary and further explained in appendix C. INTERNAL FILE LABELS System Labels Tape orders which specify labeled tapes will have a standard American National Standards Institute (ANSI) label. The system label consists of 17 characters, but only the first 12 are active. The remaining five characters will be 'x' filled. The 1990 PUMS files have a Data Set Name (DSN) of PUMStXss.Fnnxxxxx where t is A, B, or O depending on the file, ss is the United States Postal Service (USPS) State abbreviation, and nn is a two-digit number with leading zeroes identifying the tape volume sequence. (The "X", "F", and "x" in the DSN remain constant). User Labels Each user tape will have two user header labels and two user trailer labels. These labels combine information from the system label and the identification portion of the first and last record. These labels enable the user to quickly identify the beginning and ending records on each tape. User Header Labels The user header labels are designated UHL1 and UHL2. UHL1 and UHL2 repeat information from the system label in HDR1 and HDR2. User Trailer Labels The user trailer labels are designated UTL1 and UTL2. UTL1 1 ICPSR 6150 Page 21 and UTL2 contain information from the system trailer label. STATE-SPECIFIC FILE INFORMATION State-specific file information, such as record counts, is not provided in the technical documentation. However, each tape order is accompanied by a tape creation sheet. This sheet provides the file name, file label (HDR1), record size, block size, and record count. The tape creation sheet received with the tape should be filed in the technical documentation notebook or with other tape information maintained by the user. FILE STRUCTURE Each file consists of a series of 231-character logical records of two types; housing and persons. Each housing unit record is followed by a variable number of person records, one for each member of the housing unit or none if vacant, as illustrated in figure 1. Each person in group quarters has two records--a dummy "housing unit" record (most nongeographic fields are not applicable), as well as a person record. For 1990, we made several improvements to the file to aid in processing the data. Two improvements allowing users more processing flexibility are the inclusion of the housing unit serial number on both record types and the inclusion of individual weights on each record. Including the housing unit serial number on both records affords the user an option as to how to process the data-either rectangularly or hierarchically. With the introduction of individual weights, users can more closely approximate published data. Another improvement for 1990 is providing many of the recodes (data transformations) which appear on the summary tape file (STF 3A). While the changes increase the file size, we should see an associative increase in file utility. In the text of this document, the numeric identification of a particular data item is the same as its character location within a record. Items on the housing record are prefixed with an H, items on the person record with a P. For instance, Race, item P12-14, is a two-digit code beginning in character 12 of the person record. We continue to provide in the data dictionary, or record layout, mnemonic identifiers, many of which are the same as those used in 1980. Geographic identifiers and subsample identifiers appear only on the housing unit record. Thus, most tabulations of person characteristics require manipulation of both housing and person records. An item on the housing record indicates the exact number of person records following before the next housing record (PERSONS). This feature allows a program to anticipate what type of record will appear next, if necessary. 1 Page 22 ICPSR 6150 In today's data manipulation environment, users have many options for processing data and are limited only by the amount and type of resources. Most statistical software packages (e.g. BMDP, SAS, SPSS, to name a few) are capable of handling the data either hierarchically or rectangularly. Many users may still want to create extract files with any desired household data repeated with each person's record. Users with limited resources (funds, personnel, software/hardware) may want to create or obtain extracts containing only those variables of interest. All fields are numeric, except for the Record Type which are "H" and "P." FILE SIZE Every file purchased from the Census Bureau includes a printout showing the total record count. Estimated file sizes are not shown now, but in a future user note record counts for each state will be identified. RECORD SEQUENCE We release these files on a state-by-state basis. Records on these files are sorted by geographic area within state. On the 5% and 1% Samples, all households sampled within a particular PUMA appear together. PUMAs are sequenced in ascending order within State. On the 1% Sample, this means that all PUMAs with State code suppressed (i.e., shown as 99) appear on a separate file. In order to provide an extra measure of protection from disclosure of individual households within each geographic area, we scramble the records to avoid any implication of geographic information beyond that which meets Census Bureau disclosure rules for the 1990 PUMS. Person records within household are sequenced by relationship code (P2). The householder record always immediately follows the housing unit record for an occupied unit. This feature simplifies tabulation of households or families by race of householder, ancestry of householder, and even poverty status--since the desired indicators are always on the first person record. Where the household contains more than one person of a given relationship, person records appear in sequence of decreasing age (P8-9). Persons sampled from within the same group quarters are not identifiable as such, since each has an independent dummy housing unit record. MACHINE-READABLE DOCUMENTATION Every file includes a machine readable "data dictionary" or record layout. Irrespective of the PUMS sample used, the record layout is the same. A user can produce hard copy documentation for extract 1 ICPSR 6150 Page 23 files or labels for tabulations created; or with minor modifications, can use the data dictionary file with software packages or user programs to automatically specify the layout of the microdata files. Also available in machine-readable form is the PUMA Equivalency File, which lists the geographic components (counties or MCDs, places, tracts where available) and their assigned PUMA codes for the 5% and 1% samples. HANDLING INVALID CODES The data dictionary shows each category as having a unique representation. Although we reviewed test files for several states, we may have a small number of cases outside the specified range for a variable. We will correct these errors when found, but users may follow the standard census practice to assign invalid codes to the next lower numbered valid category. For example, on an allocation flag with valid codes 0, 2 and 3, a 1 would be counted with code 0, and a code of 4 or more would be counted with 3. Exceptions to this rule occur in occupation and industry codes, where invalid codes are assigned to the next higher valid category. PREPARING AND VERIFYING TABULATIONS Estimation of totals - Estimates of complete-count census figures may be made from tabulations of public use microdata samples by using a simple inflation estimate - that is, summing the weights associated with that variable; (e.g. for housing characteristics, use the housing unit weight; for persons characteristics, use the person weight.) Those users using subsample numbers to vary the sample size must apply an appropriate factor, or, otherwise adjust the weights to derive an appropriate estimation of totals. We further explain the use of weights and subsample numbers in Chapter 4. Estimation of percentages - a user can estimate percentages by simply dividing the weighted estimate of persons or housing units with a given characteristic by the weighted sample estimate for the base. Normally, this yields the same as would be obtained if one made the computation using sample tallies rather than weighted estimates. For example, the percentage of housing units with air conditioning in a one-in-one-hundred sample can be obtained by simply dividing the tally of sample housing units with air conditioning by the total number of sample housing units. Verifying tabulations - Producing desired estimates from the public-use microdata samples is relatively easy. File structure and coding of items is straightforward. There are no missing data (see the section on allocations, page 3-38). Records not applicable for each item are assigned to specific "NA" categories, and it is frequently not necessary to determine in a separate operation whether 1 Page 24 ICPSR 6150 a record is in the universe or not. PUMs "universe" and "variable" definitions may differ from other products produced from sample data primarily because of concerns about disclosure risks (e.g. PUMs files may have different topcodes from STF 3A, or the recodes may vary because the components were topcoded). A user must, however, anticipate the possibility of errors in his or her own processing. Thus, user tabulations should be verified against other available tallies. Two ways for the user to verify estimates follow: 1. Using control tabulations from the samples. As each public-use microdata sample was produced, counts of persons, housing units, vacant housing units, and group quarters persons selected into the sample were tallied within each identified geographic area. These control counts will be published as a supplement to this documentation. (In the interim, counts for specific areas may be requested from Customer Services.) If users cannot replicate these exact counts, review of the user's programs, and the shipping advices accompanying the files are in order. 2. Using published data from the 1990 censuses. Tabulations from the 1990 census data base are available in the printed census publications and on summary tape files. Users may check the reasonableness of statistics derived from public-use microdata samples against these sources. A familiarity with summary data already available may also facilitate planning of tabulations to be made from microdata. Those publications series likely to be of greatest use for this purpose are listed in Figure 5. In comparing sample tabulations with published data one must carefully note the universe of the published tabulation. For instance, on microdata records, Industry (P87-89) is reported for the civilian labor force and for persons not in the labor force who reported having worked in 1985 or later. Industry tabulations in 1990 census publications are presented only for the employed population or the experienced civilian labor force. Thus, a tally of Industry for all persons from whom industry is reported in microdata records would not correspond directly to any published tabulation. "A 1 ICPSR 6150 Page 25 user should always pay particular attention to concept definitions as presented in the glossary." One cannot, of course, expect exact agreement between census publications which are based on the complete census count, full sample estimates, or a subsample of the census sample and user estimates based on tallies of a 5-percent or smaller sample. They will inevitably differ to some extent due to chance in selection of actual cases for Public Use Microdata Samples. Since the amount of likely chance variation for a given statistic can be measured, any discrepancy beyond a certain level can be identified as a likely error in programming. Chapter 3 discusses sampling variability and its measurement. User experience has indicated that careful verification of sample tabulations is essential -- so important that it may frequently be advisable to include additional cells in a tabulation for no other reason than to provide counts or to yield marginal totals, not otherwise available, which may be verified against available tabulations. 1 Page 26 ICPSR 6150 Figure 5. 1980-1990 Subject Comparability Most of the items for 1990 are comparable to 1980. Several items found in 1980 PUMS are not in the 1990 file primarily because the inquiries were not asked or because we are providing a measure of protection for respondents. Full descriptions of item comparability are given in appendix B. However, users should read appendix C for differences in PUMS definitions and those of other census products. 1990 Items not on 1980 Files 1980 Items Not on 1990 Files Condominium fees Access to unit Employment status of parents recode Age at first marriage Flag indicating all 100% person's data Bathrooms substituted Cooking Fuel Flag indication all 100% housing unit Heating equipment data substituted Passenger elevator Gross rent as a percentage of 1989 Place of work SMSA recode Household Income Place of work place size recode Household language recode Place of work central city recode Housing unit/GQ person serial number Quarter of birth Housing unit weight Spanish surname Time of departure for work Stories in structure Linguistic isolation recode Married, spouse present/absent recode Mobile home costs Number of related children in household recode Number of stepchildren in household recode Number of persons in family recode Person's weight Presence of subfamilies in household Presence of person under 65 years in household Presence of person under 60 years in household Presence of nonrelatives in household Presence of person under 18 years in household Rental unit recode Selected monthly owner costs as a percentage of 1989 household income Value unit recode Workers in family recode Years of active military duty CONCEPTS SUBSTANTIALLY CHANGED Grade & Finished Highest Grade - now combined and grouped to show 1 ICPSR 6150 Page 27 highest level completed Race - Several categories added including 25 American Indian tribes Spanish origin - Now Hispanic origin showing an expanded list of countries 1 Page 28 ICPSR 6150 - 1 ICPSR 6150 Page 29 CHAPTER 3 - ACCURACY OF THE MICRODATA SAMPLE ESTIMATES INTRODUCTION The tabulations prepared from a public use microdata sample are based on a subset of the 1990 Census sample. The data summarized from this file are estimates of the actual figures that would have been obtained from a 100-percent enumeration. Estimates derived from this sample are expected to be different from the 100-percent figures because they are subject to sampling and nonsampling errors. Sampling error in data arises from the selection of persons and housing units to be included in the sample. Nonsampling error affects both sample and 100 percent data. Errors are introduced during the collection and processing phases of the census. A more detailed discussion of both sampling and nonsampling error is given below. In microdata samples, the basic unit is an individual housing unit and the persons who live in occupied housing units or group quarters. However, microdata records in these samples do not contain names or addresses. A more detailed discussion of methods to protect confidentiality of individual responses follows. CONFIDENTIALITY OF THE DATA To maintain the confidentiality required by law (Title 13, United States Code), the Bureau of the Census applies a confidentiality edit to the 1990 census data to assure that published data do not disclose information about specific individuals, households, or housing units. As a result, a small amount of uncertainty is introduced into the estimates of census characteristics. The sample itself provides adequate protection for most areas for which sample data are published since the resulting data are estimates of the actual counts; however, small areas require more protection. The edit is controlled so that the basic structure of the data are preserved. The confidentiality edit is implemented by selecting a small subset of individual households from the internal sample data files and blanking a subset of the data items on these household records. Responses to those data items were then imputed using the same imputation procedures that were used for nonresponse. A larger subset of households is selected for the confidentiality edit for small areas to provide greater protection for these areas. The editing process is implemented in such a way that the quality and usefulness of the data were preserved. Since microdata records are the actual housing unit and person records, the Bureau of the Census takes further steps to 1 Page 30 ICPSR 6150 prevent the identification of specific individuals, households, or housing units. The main disclosure avoidance method used is to limit the geographic detail shown in the files. A geographic area must have a minimum of 100,000 population to be fully identified. Furthermore, certain variables are topcoded, or the actual value of the characteristics is replaced by a descriptive statistic, such as the median. SOURCES OF ERRORS IN THE DATA Since the estimates that users produce are based on a sample, they may differ somewhat from 100-percent figures that would have been obtained if all housing units, persons within those housing units, and persons living in group quarters had been enumerated using the same questionnaires, instructions, enumerators, and so forth. The sample estimate also would differ from other samples of housing units, persons within those housing units, and persons living in group quarters. The deviation of a sample estimate from the average of all possible samples is called the sampling error. The standard error of a sample estimate is a measure of the variation among the estimates from all the possible samples, and thus, is a measure of the precision with which an estimate from a particular sample approximates the average result of all possible samples. The sample estimate and its estimated standard error permit the construction of interval estimates with prescribed confidence that the interval includes the average result of all samples. The method of calculating standard errors and confidence intervals for the data in the microdata samples, is described in the next section. In addition to the variability which arises from the sampling procedures, both sample data and 100-percent data are subject to nonsampling error. Nonsampling error may be introduced during any of the various complex operations used to collect and process census data. For example, operations such as editing, reviewing, or handling questionnaires may introduce error into the data. A detailed discussion of the sources of nonsampling error is given in the section on "Control of Nonsampling Error" in this chapter. Nonsampling error may affect the data in two ways. Errors OAthat are introduced randomly will increase the variability of the data and should, therefore, be reflected in the standard error. Errors that tend to be consistent in one direction will make both sample and 100-percent data biased in that direction. For example, if respondents consistently tend to underreport their income, then the resulting counts of households or families by income category will tend to be understated for the higher income categories and overstated for the lower income categories. Such biases are not reflected in the standard error. 1 ICPSR 6150 Page 31 CALCULATIONS OF STANDARD ERRORS USING TABLES A standard sampling theory text should be helpful if the user needs more information about confidence intervals and nonsampling errors. Two methods for estimating standard errors of estimated totals and percentages are described in this section. The first method is very simple. This method uses already calculated standard errors for specific sizes of estimated totals and percentages given in tables A through F, shown later in this section. The estimated standard errors shown in tables A through F were calculated assuming simple random sampling while the microdata sample (and the census sample) were selected using a systematic sampling procedure. The numbers shown in table G, referred to as design factors, are defined as the ratio of the standard error from the actual sample design to the standard error from a simple random sample. The standard errors in tables A through F used in conjunction with the appropriate design factors from table G produce a reasonable measure of reliability for microdata sample estimates. Public use microdata sample data users will receive table G, the Table of Design Factors, as a supplement to the technical documentation. An alternative methodology by which more precise standard errors can be obtained requires additional data processing and file manipulation. The trade off is more precision for more data processing. However, with the technology available today, the second method is preferable and strongly recommended. However, the standard error tables could be very useful. For instance, they would be useful when one is trying to determine, prior to purchase, whether a 1-percent sample will yield estimates of adequate precision for a given study, or whether it is necessary to use the 5-percent sample instead. For these purposes the method described in this section should produce an acceptable approximation. On the other hand, for many statistics, particularly from detailed cross-tabulations, standard errors using the second method are also applicable to a wider variety of statistics, e.g., means and ratios. To produce standard error estimates, one obtains (1) the unadjusted standard error for the characteristic that would result from a simple random sample design (of persons, families, or housing units) and estimation technique; and (2) a design factor, which partially reflects the effects of the actual sample design and estimation procedure used for the 1990 census public use microdata sample, for the particular characteristic estimated. The design factors provided in this chapter are based on computations from the full census sample and, as such, do not reflect the additional stratification used in the selection of the public use microdata samples (see Chapter 4). In general, these factors will provide conservative estimates of the standard error. In addition, these factors only pertain to individual data items (e.g., educational 1 Page 32 ICPSR 6150 attainment, employment status) and are not entirely appropriate for use with detailed cross-tabulated data. To calculate the approximate standard error of a 5-percent or 1-percent sample estimate follow the steps given below. 1. Obtain the unadjusted standard error for the sampling rate to be used from table A, C, or E, for estimated totals or from tables B, D, or F for estimated percentages. Alternately, the formula given at the bottom of each table may be used to calculate the unadjusted standard error (for sample sizes other than 5 or 1-percent see the subsampling section). In using tables A, C, or E, or corresponding formulas for estimated totals, use weighted figures rather than unweighted sample counts to select the appropriate row. To select the applicable column for person characteristics, use the total population in the area being tabulated (not just the total of the universe being examined), or use the total count of housing units if the estimated total is a housing unit characteristic. Similarly in using table B, D, or F, or the corresponding formula for estimated percentages, use weighted figures to select the appropriate column. 2. Use table G to obtain the design factor for the characteristic (e.g., place of work or educational attainment). If the estimate is a cross-tabulation of more than one characteristic, scan table G for each appropriate factor and use the largest factor. Multiply the unadjusted standard error from step 1 by the factor obtained in step 2. Example 1: Standard Error of a Total - Suppose we tally a 5-percent public use microdata sample for state A. Further, suppose that for county A, the sum of the PUMS weights for all persons is 131,220. The sum of the PUMS weights for those persons who are age 16 years and over and in the civilian labor force is 59,948. The basic standard error for the estimated total is obtained from table A or from the formula given below table A. To avoid interpolation, the use of the formula will be demonstrated here. The formula for the basic standard error, SE, is: SE(59,948) = (square root of) 19(59,948) (1-59,948/131,220) 1 ICPSR 6150 Page 33 = 787 persons The standard error of the estimated 59,948 persons 16 years and over who were in the civilian labor force is found by multiplying the basic standard error 787 by the appropriate design factor (Employment Status) from table G. Suppose the design factor for Employment Status is 1.2, then the standard error is SE(59,948) = 787(1.2) = 945 persons Note that in this example the total weighted count of persons in county A of 131,220 was used. Example 2: Standard Error of a Percent - Suppose there are 95,763 persons in county A in state A aged 16 years and over. The estimated percent of persons 16 years and over who were in the civilian labor force is 62.6. Using the formula given in table B, the unadjusted standard error is found to be approximately 0.68 percent. The standard error for the estimated 62.6 percent of persons 16 years and over who were in the civilian labor force is 0.68 (1.2) = 0.82 percentage points. Note that in this example the base is defined as the weighted count of persons 16 years old and over. A note of caution concerning numerical values is necessary. Standard errors of percentages derived in this manner are approximate. Calculations can be expressed to several decimal places, but to do so would indicate more precision in the data than is justifiable. Final results should contain no more than two decimal places. Sums and Differences - The standard errors estimated from these tables are not directly applicable to sums of and differences between two sample estimates. To estimate the standard error of a sum or difference, the tables are to be used somewhat differently in the following three situations: 1. For the sum of or difference between a sample estimate and a 100-percent value, use the standard error of the sample estimate. The complete count value is not subject to sampling error. 2. For the sum of or difference between two sample estimates, the appropriate standard error is approximately the square root of the sum of the two individual standard errors squared, that is, for standard errors: 1 Page 34 ICPSR 6150 SE and SE of estimates X and Y X Y SE = SE = sauare root of (SE )sq. + (SE )sq. (X + Y) (X - Y) X Y This method, however, will underestimate (overestimate) the standard error if the two items in a sum are highly positively (negatively) correlated or if the two items in a difference are highly negatively (positively) correlated. This method may also be used for the difference between (or sum of) sample estimates from two censuses or from a census sample and another survey. The standard error for estimates not based on the 1990 census sample must be obtained from an appropriate source outside of this appendix. 3. For the differences between two estimates, one of which is a subclass of the other, use the tables directly where the calculated difference is the estimate of interest. For example, to determine the estimate of non-Black teachers, one may subtract the estimate of Black teachers from the estimate of total teachers. To determine the standard error of the estimate of non-Black teachers apply the above formula directly. Ratios - Frequently, the statistic of interest is the ratio of two variables, where the numerator is not a subset of the denominator. For example, the ratio of teachers to students in public elementary schools. The standard error of the ratio between two sample estimates is estimated as follows: 1. If the ratio is a proportion, then follow the procedure outlined for "Totals and Percentages." 2. If the ratio is not a proportion, then approximate the standard error using the formula below. X (SEx)sq. (SEy)sq. SE = - (square root of) ---------- + --------- (X/Y) Y Xsq. Ysq. 1 ICPSR 6150 Page 35 * lower case "X" and "Y" indicate subscript here. Medians - For the standard error of the median of a characteristic, it is necessary to examine the distribution from which the median is derived, as the size of the base and the distribution itself affect the standard error. An approximate method is given here. As the first step, compute one-half of the number on which the median is based (refer to this result as N/2). Treat N/2 as if it were an ordinary estimate and obtain its standard error as instructed above. Compute the desired confidence interval about N/2. Starting with the lowest value of the characteristic, compute the frequencies in each category of the characteristic until the sum equals or first exceeds the lower limit of the confidence interval about N/2. By linear interpolation, obtain a value of the characteristic corresponding to this sum. This is the lower limit of the confidence interval of the median. In a similar manner, continue cumulating frequencies until the sum equals or exceeds the count in excess of the upper limit of the interval about N/2. Interpolate as before to obtain the upper limit of the confidence interval for the estimated median. When interpolation is required in the upper open-ended interval of a distribution to obtain a confidence bound, use 1.5 times the lower limit of the open-ended confidence interval as the upper limit of the open-ended interval. CONFIDENCE INTERVALS AND INFERENCES BASED ON THE SAMPLE A sample estimate and its estimated standard error may be used to construct confidence intervals about the estimate. These intervals are ranges that will contain the average value of the estimated characteristic that results over all possible samples, with a known probability. For example, if all possible samples that could result under the 1990 census sample design were independently selected and surveyed under the same conditions, and if the estimate and its estimated standard error were calculated for each of these samples, then: 1. Approximately 68 percent of the intervals from one estimated standard error below the estimate to one estimated standard error above the estimate would contain the average result from all possible samples. 2. Approximately 90 percent of the intervals from 1.645 times the estimated standard error below the estimate to 1.645 times the estimated standard error above the estimate would contain the average result from all possible samples. 1 Page 36 ICPSR 6150 3. Approximately 95 percent of the intervals from two estimated standard errors below the estimate to two estimated standard errors above the estimate would contain the average result from all possible samples. 1 ICPSR 6150 Page 37 Table A: Unadjusted Standard Errors for Estimated Totals, 5 Percent Sample Estimated Size of Geographic area Tabulated (2) Total (1) 100,000 250,000 500,000 750,000 1 M 5 M 10 M 25 M 1,000 140 140 140 140 140 140 140 140 2,500 220 220 220 220 220 220 220 220 5,000 300 310 310 310 310 310 310 310 10,000 410 430 430 430 430 440 440 440 15,000 490 520 530 530 530 530 530 530 25,000 600 650 670 680 680 690 690 690 75,000 600 1,000 1,100 1,130 1,150 1,180 1,190 1,190 100,000 - 1,070 1,230 1,280 1,310 1,360 1,370 1,380 250,000 - - - 1,280 1,890 2,120 2,150 2,170 500,000 - - - 1,780 2,180 2,920 3,000 3,050 750,000 - - - - 968 3,480 3,630 3,717 1,000,000 - - - - - 3,900 4,140 4,270 5,000,000 - - - - - - 6,980 8,720 10,000,000 - - - - - - - 10,680 1. For estimated totals larger than 10,000,000, the standard error is somewhat larger than the table values. The formula given below should be used to calculate the standard error. SE(Y) = (square root of) ! Y ! Where: N = Size of area 19Y !1 - --- ! Y = Estimate of ! N ! characteristic total 2. Total count of persons, housing units, or families in area if the estimated total is a person, housing unit, or family characteristic, respectively. ______________________________________________________________________ Table B: Unadjusted Standard Error for Estimated Percentages, 5 Percent Sample (Standard errors expressed in percentage points) Estimated Base (weighted total) of percentage (1) Percent 1000 1500 2500 5000 7500 10000 25000 50000 100000 250000 500000 2 or 98 1.9 1.6 1.2 0.9 0.7 0.6 0.4 0.3 0.2 0.1 0.1 5 or 95 3.0 2.4 1.9 1.3 1.1 1.0 0.6 0.4 0.3 0.2 0.1 10 or 90 4.1 3.4 2.6 1.8 1.5 1.3 0.8 0.6 0.4 0.3 0.2 15 or 85 4.9 4.0 3.1 2.2 1.8 1.6 1.0 0.7 0.5 0.3 0.2 20 or 80 5.5 4.5 3.5 2.5 2.0 1.7 1.1 0.8 0.6 0.3 0.2 25 or 75 6.0 4.9 3.8 2.7 2.2 1.9 1.2 0.8 0.6 0.4 0.3 30 or 70 6.3 5.2 4.0 2.8 2.3 2.0 1.3 0.9 0.6 0.4 0.3 35 or 65 6.6 5.4 4.2 2.9 2.4 2.1 1.3 0.9 0.7 0.4 0.3 1 Page 38 ICPSR 6150 50 6.9 5.6 4.4 3.1 2.5 2.2 1.4 1.0 0.7 0.4 0.3 1. For a percentage and/or base of percent age not shown in the table, the formula given below may be used to calculate the standard error. 19 SE(Y) = (square root of) ---p(100 - p) B Where: B = Base of estimated percentage p = Estimated percentage ---------------------------------------------------------------------- Table C: Unadjusted Standard Errors for Estimated Totals, 1 Percent Sample Estimated Size of Geographic area Tabulated (2) Total (1) 100,000 250,000 500,000 750,000 1 M 5 M 10 M 25 M 1,000 310 310 310 310 310 310 310 310 2,500 490 500 500 500 500 500 500 500 5,000 690 700 700 700 700 700 700 700 10,000 940 970 980 990 990 990 990 990 15,000 1,120 1,180 1,200 1,210 1,210 1,210 1,210 1,210 25,000 1,260 1,490 1,530 1,550 1,550 1,570 1,570 1,570 75,000 1,360 2,280 2,510 2,590 2,620 2,700 2,710 2,720 100,000 - 2,440 2,810 2,930 2,980 3,110 3,130 3,140 250,000 - - 3,520 4,060 4,310 4,850 4,910 4,950 500,000 - - - 4,060 4,970 6,670 6,860 6,960 750,000 - - - - 7,462 7,944 8,287 8,787 1,000,000 - - - - - 8,900 9,440 9,750 5,000,000 - - - - - - 15,730 19,900 10,000,000 - - - - - - - 24,370 1. For estimated totals larger than 10,000,000, the standard error is somewhat larger than the table values. The formula given below should be used to calculate the standard error. SE(Y) = (square root of) ! Y ! Where: N = Size of area 19Y !1 - --- ! Y = Estimate of ! N ! characteristic total 2. Total count of persons, housing units, or families in area if the estimated total is a person, housing unit, or family characteristic, respectively. 1 ICPSR 6150 Page 39 ______________________________________________________________________ Table D: Unadjusted Standard Error for Estimated Percentages, 1 Percent Sample (Standard errors expressed in percentage points) Estimated Base (weighted total) of percentage (1) Percent 1000 1500 2500 5000 7500 10000 25000 50000 100000 250000 500000 2 or 98 4.4 3.6 2.8 2.0 1.6 1.4 0.9 0.6 0.4 0.3 0.2 5 or 95 6.9 5.6 4.3 3.1 2.5 2.2 1.4 1.0 0.7 0.4 0.3 10 or 90 9.4 7.7 6.0 4.2 3.4 3.0 1.9 1.3 0.9 0.6 0.4 15 or 85 11.2 9.2 7.1 5.0 4.1 3.6 2.2 1.6 1.1 0.7 0.5 20 or 80 12.6 10.3 8.0 5.6 4.6 4.0 2.5 1.8 1.3 0.8 0.6 25 or 75 13.6 11.1 8.6 6.1 5.0 4.3 2.7 1.9 1.4 0.9 0.6 30 or 70 14.4 11.8 9.1 6.4 5.3 4.6 2.9 2.0 1.4 0.9 0.6 35 or 65 15.0 12.8 9.5 6.7 5.5 4.7 3.0 2.1 1.5 0.9 0.7 50 15.8 12.8 9.9 7.0 5.7 5.0 3.1 2.2 1.6 1.0 0.7 1. For a percentage and/or base of percent age not shown in the table, the formula given below may be used to calculate the standard error. 99 SE(p) = (square root of)---p(100 - p) B Where: B = Base of estimated percentage (weighted total) p = Estimated percentage ---------------------------------------------------------------------- Table E: Unadjusted Standard Errors for Estimated Totals, 3 Percent Sample Estimated Size of Geographic area Tabulated (2) Total (1) 50K 100K 250K 500K 1,000K 5,000K 10,000K 25,000K 1,000 180 180 180 180 180 180 180 180 2,500 280 280 290 290 290 290 290 290 5,000 390 390 400 400 410 410 410 410 10,000 510 540 560 570 570 570 570 570 15,000 590 650 680 690 700 700 700 700 25,000 640 780 860 880 890 900 900 900 75,000 - 780 1,310 1,440 1,500 1,550 1,560 1,560 100,000 - - 1,400 1,610 1,710 1,780 1,790 1,800 250,000 - - - 2,010 2,470 2,780 2,810 2,830 500,000 - - - - 2,850 3,820 3,920 3,980 1 Page 40 ICPSR 6150 750,000 - - - - 2,460 4,540 4,736 4,580 1,000,000 - - - - - 5,090 5,400 5,850 5,000,000 - - - - - - 8,990 11,380 10,000,000 - - - - - - - 13,930 1. For estimated totals larger than 10,000,000, the standard error is somewhat larger than the table values. The formula given below should be used to calculate the standard error. SE(Y) = (square root of) 97 ! Y ! ---Y !1 - --- ! 3 ! N ! Where: N = Size of area Y = Estimate of characteristic total 2. Total count of persons, housing units, or families in area if the estimated total is a person, housing unit, or family characteristic, respectively. ______________________________________________________________________ Table F: Unadjusted Standard Error for Estimated Percentages, 3 Percent Sample (Standard errors expressed in percentage points) Estimated Base (weighted total) of percentage (1) Percent 1000 1500 2500 5000 7500 10000 25000 50000 100000 250000 500000 2 or 98 2.5 2.0 1.6 1.1 .9 .8 .5 .6 .2 .1 .1 5 or 95 3.9 3.2 2.4 1.7 1.4 1.2 .8 .0 .4 .2 .2 10 or 90 5.4 4.4 3.4 2.4 2.0 1.7 1.1 .3 .5 .3 .2 15 or 85 6.4 5.2 4.1 2.9 2.3 2.1 1.3 .6 .6 .4 .3 20 or 80 7.2 5.9 4.5 3.2 2.6 2.3 1.4 1.0 .7 .5 .3 25 or 75 7.8 6.4 4.9 3.5 2.8 2.5 1.6 1.1 .8 .5 .3 30 or 70 8.2 6.7 5.2 3.7 3.0 2.6 1.6 1.1 .8 .5 .3 35 or 65 8.6 7.0 5.4 3.8 3.1 2.7 1.7 1.2 .9 .5 .4 50 9.0 7.3 5.7 4.0 3.3 2.8 1.8 1.3 .9 .6 .4 1. For a percentage and/or base of percent age not shown in the table, the formula given below may be used to calculate the standard error. 97 SE(p) = (square root of) ---p(100 - p) 3B Where: B = Base of estimated 1 ICPSR 6150 Page 41 percentage (weighted total) p = Estimated percentage ---------------------------------------------------------------------- Table G. Standard Error Design Factors-United States (Percent of persons or housing units in sample) Characteristic Design factors POPULATION Age............................................................ Sex............................................................ Race........................................................... Hispanic origin (of any race).................................. Marital status................................................. Household type and relationship................................ Children ever born............................................. Work disability and mobility limitation status................. Ancestry....................................................... Place of birth................................................. Citizenship.................................................... Migration (Residence in 1985).................................. Year of entry.................................................. Language spoken at home and ability to speak English........... Educational attainment......................................... School enrollment.............................................. Type of residence (urban/rural)................................ Household type................................................. Family type.................................................... Group quarters................................................. Subfamily type and presence of children........................ Employment status.............................................. Industry....................................................... Occupation..................................................... Class of worker................................................ Hours per week and weeks worked in 1989........................ Number of workers in family.................................... Place of work.................................................. Means of transportation to work................................ Travel time to work............................................ Vehicle occupancy.............................................. Time of departure for work..................................... Type of income in 1989......................................... Household Income in 1989....................................... Family income in 1989.......................................... Poverty status in 1989 (persons)............................... Poverty status in 1989 families)............................... Armed Forces and veteran status................................ 1 Page 42 ICPSR 6150 HOUSING Age of householder............................................. Race of householder............................................ Hispanic origin of householder................................. Type of residence (urban/rural................................. Condominium status............................................. Units in structure............................................. Tenure......................................................... Occupancy status............................................... Value.......................................................... Gross rent..................................................... Household income in 1989....................................... Year structure built........................................... Rooms, bedrooms................................................ Kitchen facilities............................................. Source of water, plumbing facilities........................... Sewage disposal................................................ House heating fuel............................................. Telephone in housing unit...................................... Vehicles available............................................. Year householder moved into structure.......................... Mortgage status and monthly mortgage costs..................... Mortgage status and selected monthly owner costs............... Gross rent as a percentage of household income in 1989......... Household income in 1989 by selected owner costs as a percentage of household income............................... 1 ICPSR 6150 Page 43 The intervals are referred to as 68 percent, 90 percent, and 95 percent confidence intervals, respectively. The average value of the estimated characteristic that could be derived from all possible samples is or is not contained in any particular computed interval. Thus, we cannot make the statement that the average value has a certain probability of falling between the limits of the calculated confidence interval. Rather, one can say with a specified probability of confidence, that the calculated confidence interval includes the average estimate from all possible samples (approximately the 100-percent value). Confidence intervals also may be constructed for the ratio, sum of, or difference between two sample figures. This is done by first computing the ratio, sum, or difference, then obtaining the standard error of the ratio, sum, or difference (using the formulas given earlier), and finally forming a confidence interval for this estimated ratio, sum, or difference as above. One can then say with specified confidence that this interval includes the ratio, sum, or difference that would have been obtained by averaging the results from all possible samples. The estimated standard errors given in this chapter do not include all portions of the variability due to nonsampling error that may be present in the data. The standard errors reflect the effect of simple response variance, but not the effect of correlated errors introduced by enumerators, coders, or other field or processing personnel. Thus, the standard errors calculated represent a lower bound of that total error. As a result, confidence intervals formed using these estimated standard errors may not meet the stated levels of confidence (i.e., 68, 90, or 95 percent). Thus, some care must be exercised in the interpretation of the data in this data product based on the estimated standard errors. In example 1, the standard error of the 59,948 persons 16 years and over in county A in state A who were in the civilian labor force was found to be 945. Thus, a 90 percent confidence interval for this estimated total is found to be: (59,948 - 1.645 (945)) to (59,948 + 1.645(945)) or 58,393 to 61,502 One can say, with about 90 percent confidence, that this interval includes the value that would have been obtained by averaging the results from all possible samples. The following is an illustration of the calculation of 1 Page 44 ICPSR 6150 standard errors and confidence intervals when a difference between two sample estimates is obtained. For example, suppose the number of persons in county B age 16 years and over who were in the civilian labor force was 69,314 and the total number of persons 16 years and over was 116,666. Further, suppose the population of county B was 225,225. Thus, the estimated percentage of persons 16 years and over who were in the civilian labor force is 59.4 percent. The unadjusted standard error from table B is 0.63 percentage points. The design factors table (table G) shows the design factor to be 1.1 for "Employment Status." Thus, the approximate standard error of the percentage (59.4 percent) is 0.63 x 1.2 = 0.76 percentage points. Now suppose that one wished to obtain the standard error of the difference between county A and county B of the percentage of persons who were 16 years and over and who were in the civilian labor force. The difference in the percentages of interest for the two cities is: 62.6 - 59.4 = 3.2 percent. Using the results of the previous example: SE(3.2) = (square root of)(SE(62.6))Ø2 + (SE(59.4))Ø2 = (square root of)(0.82)Ø2 + (.76)Ø2 = 1.12 percentage points The 90 percent confidence interval for the difference is formed as before: (3.20 - 1.645(1.12)) to (3.20 + 1.645(1.12)) or 1.36 to 5.04 One can say with 90 percent confidence that the interval includes the difference that would have been obtained by averaging the results from all possible samples. When, as in this example, the interval does not include zero, one can conclude, again with 90 percent confidence, that the difference observed between the two counties on this characteristic is greater than can be attributed to sampling error. For reasonably large samples, ratio estimates are normally distributed, particularly for the census population. Therefore, if 1 ICPSR 6150 Page 45 we can calculate the standard error of a ratio estimate, then we can from a confidence interval around the ratio. Suppose that one wished to obtain the standard error of the ratio of the estimate of persons who were 16 years and over and who were in the civilian labor force in county A to the estimate of persons who were 16 years and over and who were in the civilian labor force in county B. The ratio of the two estimates of interest is: 59,948 / 69,314 = .86 ! 59948 ! 953Ø2 1145Ø2 SE(.86) = ! ------- ! (square root of) -------- + --------- ! 69314 ! (59948)Ø2 (69314)Ø2 = .02 Using the results above, the 90 percent confidence interval for this ratio would be: (.86 - 1.645(.02)) to (0.86 + 1.645(.02)) or .83 to .89 SELECTING AN APPROPRIATE SAMPLE SIZE - One virtue in the use of the tables A through F for calculating standard errors and confidence intervals is that this method can be employed prior to making any sample tabulation, and thus, can help the user decide prior to purchase whether a 5-percent or 1-percent sample size is most appropriate for a proposed study. Suppose that in the foregoing example, the 59,948 figure was a guess, perhaps based on published data. The confidence interval could be calculated as above. In this case, tabulating a 5-percent sample for this particular characteristic would result in a 90 percent confidence interval 58,393 to 61,502. The width of this interval is 3,109. Tabulating from a 1-percent sample for the same characteristic would result in a confidence interval of 56,403 to 63,492. The width of the interval from the 1-percent sample is 7,089 (over two times the width of the confidence interval from the 5-percent sample). Another criterion used in making this type of decision is the coefficient of variation (CV). The CV is a measure of reliability and is defined as the ratio of the standard error of the estimate and the absolute value of the expected value of the estimate. To get an estimate of the CV, substitute the estimate itself for the expected value in the CV formula. In this example, if the 59,948 estimate is obtained from the 5-percent sample, the CV would be 1.4 percent. If the 1-percent sample is tallied to get the estimate then the CV would be 3 percent. The smaller the CV, the 1 Page 46 ICPSR 6150 more reliable the estimate. There is no particular rule of thumb that dictates how large a confidence interval or CV is acceptable. This depends on the relative precision necessary for a particular application as balanced against the relative cost of tabulating microdata samples of the various sizes. USING TABLE A THROUGH F FOR OTHER SAMPLE SIZES Tables A through F may also be used to approximate the unadjusted standard errors for other sample sizes by adjusting for the sample size desired. The adjustment for sample size is obtained as follows: Let f1 be the sampling rate in any of the tables A through F, and f2 be the sampling rate for the sample size to be used. The adjustment for sample size can be read from the following table: f2 Sample Size Adjustment Factor For example, if the user were to select a subsample of one half of a 1-percent sample, i.e., f2 = .005, then the standard errors shown in tables C or D for a 1-percent sample must be multiplied by 1.42 to obtain the standard errors for a .005 sample. The factor of 1.42 shows that the standard errors increase by 42 percent when the sample size is halved. The principle is also applicable when combining microdata samples to achieve a sample size larger than 5 percent. If, for example, all three samples are combined for the same area to obtain an estimate of a characteristic for the elderly population, the standard errors for this sample size (i.e., 11 percent) can be obtained by multiplying those shown in tables A and B by .65. Thus, the increase from a 5-percent to a 11-percent sample reduces the standard error by 35 percent. Alternatively, the user may wish to use the following formulas to directly calculate the unadjusted standard errors. For estimated totals, calculate as Se(Y) ! 1 ! Se(Y) = (square root of) ! --- - 1 ! Y(1 - Y/N) 1 ICPSR 6150 Page 47 ! f ! 2 where N = size of area tabulated Y = estimate (weighted) of characteristic total. Example 1 shows the unadjusted standard error for the figure 59,948 to be 787. Using the above formula with f2 = .11 yields an unadjusted standard error SE() = 513 for a 35 percent reduction in the standard error as shown in the above table. For a estimated percentage, calculate ! 1 ! P(100 - P) Se(P) = (square root of) ! --- - 1 ! ---------- ! f ! B 2 where P = estimated percentage and B = base of estimated percentage (weighted estimate) ESTIMATION OF STANDARD ERRORS DIRECTLY FROM THE MICRODATA SAMPLES Use of tables or formulas to derive approximate standard error as discussed above is simple and does not complicate processing. Nonetheless, a more accurate estimate of the standard error can be obtained from the samples themselves, using the random group method. Using this method it is also possible to compute standard errors for mean ratios, indexes, correlation coefficients, or other statistics for which the tables or formulas presented earlier do not apply. The random group method does increase processing time somewhat since it requires that the statistic of interest, for example a total, be computed separately for each of up to 100 random groups. The variability of that statistic for the sample as a whole is estimated from the variability of the statistic among the various random groups within the sample. The procedure for calculating a standard error by the random group method for various statistics is given below. TOTALS - to obtain the standard errors of estimated totals the following method should be used. The random groups estimate of variance of X is given by _t_ ! _t_ !Ø2 1 Page 48 ICPSR 6150 ! T ! < ! 1 ! < !! var(X) = ! --- ! > ! Xg - --- ! > Xg !! ! T-1 ! <___ ! T ! <___ !! g=1 ! g=1 ! or the computational formula note - lowercase here is the equivalent of subscript _t_ ! t ! < var(X) = ! --- ! > XgØ2 - t XgØ-2 ! t-1 ! <___ g=1 where t = number of random groups Xg = the weighted microdata sample total of the characteristic of interest from the g-th random group. _t_ _ < Xg = > Xg/t, the average random group total <___ g=1 The standard error of the estimated total is the square root of var(X). It is suggested that t=100 for estimating the standard error of a total since, as it is discussed in the next chapter, each of the sample records was assigned a two-digit subsample number sequentially from 00 to 99. The two-digit number can be used to form 100 random groups. For example, a sample case with 01 as the two-digit number will be in random group 1. All sample cases with 02 as the two digit number will be in random group 2, etc., up to 00 as the one- hundredth random group. The reliability of the random group variance estimator is a function of both the kurtosis of the estimator and the number of groups t. If t is small, the coefficient of variation (CV) will be large, and therefore, the variance estimator will be of low precision. In general, the larger t is, the more reliable the variance estimator will be.1 PERCENTAGES, RATIOS, AND MEANS - To obtain the estimated standard error of a percent, ratio, or mean, the following method should be used. Let 1 ICPSR 6150 Page 49 x r = --- be the estimated percent, ratio, or mean y where and y = the estimated totals as defined above for the X and Y characteristics. For the case where BOTH numerator and denominator are obtained from the full microdata sample then the variance of R is given by _t_ ! T ! ! 1 !Ø2 < var(R) = ! --- ! ! - ! > (Xg - RYg)Ø2 ! T-1 ! ! y ! <___ g=1 where T and Xg are defined above, Y = the weighted full microdata sample total for the y characteristic, and Yg = the corresponding weighted total for the g-th random group. CORRELATION COEFFICIENTS, AND REGRESSION COEFFICIENTS AND COMPLEX STATISTICS - The random group method for computing the variance of correlation coefficients, regression coefficients, and other complex nonlinear statistics may be expressed as: ___ T < Var(THETA) = --- > (THETA g - THETA)Ø2 T-1 <___ g=1 where THETA g = the weighted estimate (at the tabulation area level) of the statistic of interest computed from the g-th random group, and THETA = corresponding weighted estimate computed from the full microdata sample. Care must be exercised when using this variance estimator for complex nonlinear statistics as its properties have not been fully explored for such statistics. In particular, the choice of the number of random groups must be considered more carefully. When using the 5-percent sample, use of t=100 for all areas tabulated is recommended. When using the 1-percent sample or samples having a smaller sampling fraction, the user should consider using a smaller number of random groups to insure that each random group contains at 1 Page 50 ICPSR 6150 least 25 records. Fewer than 100 random groups can be formed by appropriate combination of the two-digit subsample numbers. For example, to construct 50 random groups assign all records in which the subsample number is 01 or 50 to the first random group; all records in which the subsample number is 02 or 52 to the second random group, etc. Finally, assign all records in which the subsample number is 00 or 50 to random group 50. Ten random groups can be constructed by including all records having subsample numbers with the same "units" digit in a particular random group. For example, subsample numbers 00,10,...,90 would form one random group; subsample numbers 01,11,...,91 would form a second random group, etc. STANDARD ERRORS FOR SMALL ESTIMATES Percentage estimates of zero and estimated totals of zero are subject to both sampling and nonsampling error. While the magnitude of the error is difficult to quantify, users should be aware that such estimates are nevertheless subject to both sampling and nonsampling error even though in the case of zero estimates the corresponding random groups estimate of variance will be zero. A second point concerning standard errors, the standard error estimates obtained using the random groups method do not include all components of the variability due to nonsampling error that may be present in the data. Therefore, the standard error calculated using the methods described in this section represent a lower bound for the total error. Data users should be aware that in general confidence intervals formed using these estimated standard errors do not meet the stated levels of confidence. Data users are advised to be conservative when making inferences from the data provided in this data product. CONTROL OF NONSAMPLING ERROR As mentioned earlier, both sample and 100- percent data are subject to nonsampling error. This component of error could introduce serious bias into the data, and the total error could increase dramatically over that which would result purely from sampling. While it is impossible to eliminate completely nonsampling error from an operation as large and complex as the decennial census, the Bureau of the Census attempted to control the sources of such error during the collection and processing operations. Described below are the primary sources of nonsampling error and the programs instituted for control of this error. The success of these programs, however, was contingent upon how well the instructions actually were carried out during the census. As part of the 1990 census evaluation program, both the effects of these programs and the amount of error remaining after their application will be evaluated. 1 ICPSR 6150 Page 51 UNDERCOVERAGE--It is possible for some households or persons to be missed entirely by the census. The undercoverage of persons and housing units can introduce biases into the data. Several coverage improvement programs were implemented during the development of the census address list and census enumeration and processing to minimize undercoverage of the population and housing units. These programs were developed based on experience from the 1980 census and results from the 1990 census testing cycle. In developing and updating the census address list, the Census Bureau used a variety of specialized procedures in different parts of the country. o In the large urban areas, the Census Bureau purchased and geocoded address lists. Concurrent with geocoding, the United States Postal Service (USPS) reviewed and updated this list. After the postal check, census enumerators conducted a dependent canvass and update operation. Prior to mailout, in the fall of 1989, local officials were given the opportunity to examine block counts of address listings (local review) and identify possible errors, and the USPS conducted a final review. o In small cities, suburban areas, and selected rural parts of the country, the Census Bureau created the address list through a listing operation. The USPS reviewed and updated this list, and the Census Bureau reconciled USPS corrections and updated through a field operation. In the fall of 1989, local officials participated in reviewing block counts of address listings. Prior to mailout, the USPS conducted a final review. o The Census Bureau (rather than the USPS) conducted a listing operation in the fall of 1989 and delivered census questionnaires in selected rural and seasonal housing areas in March of 1990. In some inner-city public housing developments, whose addresses had been obtained via the purchased address list noted above, census questionnaires were also delivered by Census Bureau enumerators. Coverage improvement programs continued during and after mailout. A recheck of units initially classified as vacant or nonexistent further improved the coverage of persons and housing units. All local officials were given the opportunity to participate 1 Page 52 ICPSR 6150 in a post-census local review, and census enumerators conducted an additional recanvass. In addition, efforts were made to improve the coverage of unique population groups, such as the homeless and parolees/probationers. Computer and clerical edits and telephone and personal visit followup also contributed to improved coverage. More extensive discussion of the programs implemented to improve coverage will be published by the Census Bureau when the evaluation of the coverage improvement program is completed. RESPONDENT AND ENUMERATOR ERROR--The persons answering the questionnaire or responding to the questions posed by an enumerator could serve as a source of error, although the questions were phrased as clearly as possible based on precensus tests, and detailed instructions for completing the questionnaire were provided to each household. In addition, respondents' answers were edited for completeness and consistency, and problems were followed up as necessary. The enumerator may misinterpret or otherwise incorrectly record information given by a respondent; may fail to collect some of the information for a person or household; or may collect data for households that were not designated as part of the sample. To control these problems, the work of enumerators was monitored carefully. Field staff were prepared for their tasks by using standardized training packages that included hands-on experience in using census materials. A sample of the households interviewed by enumerators for nonresponse were reinterviewed to control for the possibility of data for fabricated persons being submitted by enumerators. Also, the estimation procedure was designed to control for biases that would result from the collection of data from households not designated for the sample. PROCESSING ERROR--The many phases involved in processing the census data represent potential sources for the introduction of nonsampling error. The processing of the census questionnaires includes the field editing, followup, and transmittal of completed questionnaires; the manual coding of write-in responses; and the electronic data processing. The various field, coding and computer operations undergo a number of quality control checks to insure their accurate application. NONRESPONSE--Nonresponse to particular questions on the census questionnaire allows for the introduction of bias into the data, since the characteristics of the nonrespondents have not been observed and may differ from those reported by respondents. As a result, any imputation procedure using respondent data may not completely reflect this difference either at the elemental level (individual person or housing unit) or on the average. Some protection against the introduction of large biases is afforded by minimizing nonresponse. In the census, nonresponse was reduced 1 ICPSR 6150 Page 53 substantially during the field operations by the various edit and followup operations aimed at obtaining a response for every question. Characteristics for the nonresponses remaining after this operation were imputed by the computer by using reported data for a person or housing unit with similar characteristics. EDITING OF UNACCEPTABLE DATA The objective of the processing operation is to produce a set of data that describes the population as accurately and clearly as possible. To meet this objective, questionnaires were edited during field data collection operations for consistency, completeness, and acceptability. Questionnaires also were reviewed by census clerks for omissions, certain specific inconsistencies, and population coverage. For example, write-in entries such as "Don't know" or "NA" were considered unacceptable. For some district offices, the initial edit was automated; however, for the majority of the district offices, it was performed by clerks. As a result of this operation, a telephone or personal visit followup was made to obtain missing information. Potential coverage errors were included in the followup, as well as a sample of questionnaires with omissions and/or inconsistencies. Subsequent to field operations, remaining incomplete or inconsistent information on the questionnaire was assigned using imputation procedures during the final automated edit of the collected data. Imputations, or computer assignments of acceptable codes in place of unacceptable entries or blanks, are needed most often when an entry for a given item is lacking or when the information reported for a person or housing unit on that item is inconsistent with other information for that same person or housing unit. As in previous censuses, the general procedure for changing unacceptable entries was to assign an entry for a person or housing unit that was consistent with entries for persons or housing units with similar characteristics. The assignment of acceptable codes in place of blanks or unacceptable entries enhances the usefulness of the data. Another way in which corrections were made during the computer editing process was through substitution; that is, the assignment of a full set of characteristics for a person or housing unit. When there was an indication that a housing unit was occupied but the questionnaire contained no information for the people within the household or the occupants were not listed on the questionnaire, a previously accepted household was selected as a substitute, and the full set of characteristics for the substitute was duplicated. The assignment of the full set of housing characteristics occurred when there was no housing information available. If the housing unit was determined to be occupied, the housing characteristics were assigned from a previously processed occupied unit. If the housing unit was 1 Page 54 ICPSR 6150 vacant, the housing characteristics were assigned from a previously processed vacant unit. USE OF ALLOCATION FLAGS IN THESE FILES As a result of the editing there are no blank fields or missing data in public use microdata sample files. Each field contains a data value or a "not applicable" indicator, except for the few items where allocation was not appropriate and a "not reported" indicator is included. For every subject item it is possible for the user to differentiate between entries which were allocated, by means of "allocation flags" in items H161 through H198, and P186 through P233 in the microdata files. For all items it is possible to compute the allocation rate and, if the rate is appreciable, compute the distribution of actually observed values (with allocated data omitted) and compare it with the overall distribution including allocated values. The flags indicate the changes in values between input and output. These flags may indicate up to four possible types of allocations: A. Pre-edit - When the original entry was rejected because it fell outside the range of acceptable values. B. Consistency - Imputed missing characteristics based on other information recorded for the person or housing unit. C. Hot Deck - Supplied the missing information from the record of another person or housing unit. D. Cold Deck - Supplied missing information from a predetermined distribution. In general, the allocation procedures provide better data than could be obtained by simply weighting up the observed distribution to account for missing values. The procedures reflect local variations in characteristics as well as variations among the strata used in imputation. There are, however, certain circumstances where allocated data may introduce undesirable bias. It may be particularly important to analyze allocations of data in detailed studies of subpopulations or in statistics derived from cross- classification of variables, such as correlation coefficients or measures of regression. The degree of editing required was greater for some subjects than for others. While the allocation procedure was designed to yield appropriate statistics for the overall distribution or for specific subpopulations (the strata used in the 1 ICPSR 6150 Page 55 allocation process), allocated characteristics will not necessarily observe a valid relationship with other observed variables for the same individual. For example, consider a tabulation of persons 80 years old and over by income. Income allocations were made separately for different age groupings, including the category 65 years old and over, but not separately for persons 80 years old and over. Since persons 65 to 70 or 75 are more likely to have significant earnings than persons 80 or over, allocated income data for the latter group might be biased upward. Thus, if the rate of allocations for the group is appreciably large, and a bias in the allocated value is evident, it may be desirable to exclude allocated data from the analysis. It should also be apparent from this illustration that knowledge of the specific allocation procedures is valuable in detailed subject analysis. Descriptions of the editing and allocation procedures for each item are being incorporated in the History of the 1990 Census of Population and Housing to be published later. A user may contact either the Population Division or Housing and Households Economic Statistics Division, Bureau of the Census, if more information is desired on the allocation scheme for a specific subject item. 1 Page 56 ICPSR 6150 - 1 ICPSR 6150 Page 57 CHAPTER 4 - SAMPLE DESIGN AND ESTIMATION SAMPLE DESIGN AND ESTIMATION FOR THE PUBLIC USE MICRODATA SAMPLES This chapter discusses the selection procedure for the public use microdata samples in terms of four major operations, (1) the selection of the full 1990 census sample, (2) the estimation procedure for the full census sample, and (3) the selection of the public use microdata samples from the persons and housing units included in the full 1990 census sample, and (4) estimation for the PUMS samples. PRODUCING ESTIMATES OR TABULATIONS Estimation of totals and percentages - The 1980 Public Use Microdata Samples (PUMS) were self-weighted. It is very important to note that the 1990 PUMS samples are not self-weighted. To produce estimates on tabulations of 100 percent characteristics from the PUMS files simply add the weights of all persons or housing units that possess the characteristic of interest. For instance, if the characteristic of interest is total number of Hispanic males aged 5-17, simply determine the sex, age, and Hispanic origin of all persons and cumulate the weights of those who match the characteristic of interest. The PUMS weight is a function of the full census sample weight and the PUMS sample design. To get estimates of proportions simply divide the weighted estimate of persons or housing units with a given characteristic by the base sample estimate. For example, the proportion of owner occupied housing units with plumbing facilities is obtained by dividing the PUMS estimate of owner occupied housing units with plumbing facilities by the PUMS estimates of total housing units. To get estimates of characteristics such as the total number of related children in households for (housing unit level aggregates), simply multiply the PUMS weight by the value of the characteristic and sum across all household records. If the desired estimate is the number of households with at least one related child in household add the PUMS householder weight for all households with a value not equal to zero for the characteristic. SAMPLE DESIGN Every person and housing unit in the United States was asked certain basic demographic questions (for example, race, age, relationship, housing value, or rent). A sample of these persons and housing units was asked more detailed questions about such items as income, occupation, and housing costs in addition to the basic demographic and housing information. The primary sampling unit for 1 Page 58 ICPSR 6150 the 1990 census was the housing unit, including all occupants. For persons living in group quarters, the sampling unit was the person. Persons in group quarters were sampled at a 1-in-6 rate. The sample designation method depended on the data collection procedures. Approximately 95 percent of the population was enumerated by the mailback procedure. In these areas, the Bureau of the Census either purchased a commercial mailing list, which was updated by the United States Postal Service and Census Bureau field staff, or prepared a mailing by canvassing and listing each address in the area prior to Census Day. These lists were computerized and the appropriate units were electronically designated as sample units. The questionnaires were either mailed or hand delivered to the addresses with instructions on how to complete and mail back the form. Housing units in governmental units with a precensus (1988) estimated population of fewer than 2,500 persons were sampled at 1-in-2. Governmental units were defined for sampling purposes as all incorporated places, all counties, all county equivalents such as parishes in Louisiana, and all minor civil divisions in Connecticut, Maine, Massachusetts, Michigan, Minnesota, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, Vermont, and Wisconsin. Housing units in tracts and block numbering areas (BNAs) with a precensus housing unit count below 2,000 housing units were sampled at 1-in-6 for those portions not in small governmental units. Housing units within census tracts and BNAs with 2,000 or more housing units were sampled at 1-in-8 for those portions not in small governmental units. In list/enumerate areas (about 5 percent of the population) each enumerator was given a blank address register with designated sample lines. Beginning about Census Day, the enumerator systematically canvassed the area and listed all housing units in the address register in the order they were encountered. Completed questionnaires, including sample information for any housing unit listed on a designated sample line, were collected. For all governmental units with fewer than 2,500 persons in list/enumerate areas, a 1-in-2 sampling rate was used. All other list/enumerate areas were sampled at 1-in-6. Housing units in American Indian reservations, Tribal Jurisdiction Statistical areas, and Alaska Native villages were sampled according to the same criteria as other governmental units, except the sampling rates were based on the size of the American Indian and Alaska native population in those areas as measured in the 1980 census. Trust lands were sampled at the same rate as their associated American Indian reservations. Census designated places in Hawaii were sampled at the same rate as governmental units because the Census Bureau does not recognize incorporated places in Hawaii. The purpose of using variable sampling rates was to provide relatively more reliable estimates for small areas and decrease 1 ICPSR 6150 Page 59 respondent burden in more densely populated areas while maintaining data reliability. When all sampling rates were taken into account across the nation, approximately one out of every six housing units in the nation was included in the 1990 census sample. ESTIMATION PROCEDURE Estimates from the census sample were obtained from an iterative ratio estimation procedure (iterative proportional fitting) resulting in the assignment of a weight to each sample person or housing unit record. For any given tabulation area, a characteristic total was estimated by summing the weights assigned to the persons or housing units processing the characteristic in the tabulation area. Estimates of family or household characteristics were based on the weight assigned to the person designated as householder. Each sample person or housing unit record was assigned exactly one weight to be used to produce estimates of all characteristics. For example, if the weight given to a sample person or housing unit had the value 6, all characteristics of that person or housing unit would be tabulated with the weight of 6. The estimation procedure, however, did assign weights varying from person to person or housing unit to housing unit. The estimation procedure used to assign the weight was performed in geographically defined "weighting areas". Weighting areas were generally formed of contiguous portions of geography which closely agreed with census tabulation areas within counties. Weighting areas were never allowed to cross state or county boundaries. In small counties with a sample unit below 400 persons, the minimum required sample condition was relaxed to permit the entire county to become a weighting area. Within a weighting area, the ratio estimation procedure for persons was performed in four stages. For persons, the first stage applied 17 household-type groups. The second stage used two groups: sampling rate of 1-in-2 and sampling rate below 1-in-2. The third stage used the dichotomy householder/nonhouseholders. The fourth stage applied 180 aggregate age/sex/Hispanic origin/race categories. The stages were as follows: Stage I: Type of Household Group Persons in Housing Units With a Family With Own Children Under 18 1 2 persons in housing unit 2 3 persons in housing unit 3 4 persons in housing unit 1 Page 60 ICPSR 6150 4 5 to 7 persons in housing unit 5 8 or more in housing unit Persons in Housing Units With a Family Without Own Children Under 18 6-10 2 through 8 or more persons in housing unit Persons in All Other Housing Units 11 1 person in housing unit 12-16 2 through 8 or more persons in housing unit Persons in Group Quarters 17 Persons in Group Quarters Stage II: Sampling Rates 1 Sampling rate of 1-in-2 2 Sampling rate less than 1-in-2 Stage III: Householder/Nonhouseholder 1 Householder 2 Nonhouseholder Stage IV: Age/Sex/Hispanic origin/Race White Persons of Hispanic origin Male 1 0 to 4 years of age 2 5 to 14 years of age 3 15 to 19 years of age 4 20 to 24 years of age 5 25 to 34 years of age 6 35 to 54 years of age 7 55 to 64 years of age 8 65 to 74 years of age 9 75 years of age or older 1 ICPSR 6150 Page 61 Female 10-18 Same age categories as groups 1 through 9. Persons Not of Hispanic origin 19-36 Same age and sex categories as groups 1 through 18. Black 37-72 Same age/sex/Hispanic origin categories as groups 1 through 36 Asian or Pacific Islander 73-108 Same age/sex/Hispanic origin categories as groups 1 through 36 American Indian, Eskimo or Aleut 109-144 Same age/sex/Hispanic origin categories as groups 1 through 36 Other Race (includes those races not listed above) 145-180 Same age/sex/Hispanic origin categories as groups 1 through 36 Within a weighting area, the first step in the estimation procedure was to assign an initial weight to each sample person record. This weight was approximately equal to the inverse of the probability of selecting a person for the census sample. The next step in the estimation procedure, prior to iterative proportional fitting, was to combine categories in each of the four estimation stages, when needed, to increase the reliability of the ratio estimation procedure. For each stage, any group that did not meet certain criteria for the unweighted sample count or for the ratio of the 100 percent to the initially weighted sample count, was combined, or collapsed, with another group in the same stage according to a specified collapsing pattern. At the forth stage, an additional criterion concerning the number of 100-percent persons in each race/Hispanic origin category was applied. As the final step, the initial weights underwent four stages of ratio adjustment applying the grouping procedures described above. At the first stage, the ratio of the 100- percent to the sum of the initial weights for each sample person was computed for each stage I group. The initial weight assigned to each person in a group was then multiplied by the stage I group ratio to produce an adjusted weight. In stage II, the stage I adjusted weights were again adjusted by the ratio of the 100-percent to the sum of the stage I weights for 1 Page 62 ICPSR 6150 sample persons in each stage II group. Next, at stage III, the stage II weights were adjusted by the ratio of the 100-percent to the sum of the stage II weights for sample persons in each stage III group. Finally, at stage IV, the stage III weights were adjusted by the ratio of the 100-percent to the sum of the stage III weights for sample persons in each stage IV group. The four stages of ratio adjustment were performed two times (two iterations) in the order given above. The weights obtained from the second iteration for stage IV were assigned to the sample person records. However, to avoid complications in rounding for tabulated data, only whole number weights were assigned. For example, if the final weight of the persons in a particular group was 7.25 then 1/4 of the sample persons in this group were randomly assigned a weight of 8, while the remaining 3/4 received a weight of 7. The ratio estimation procedure for housing units was essentially the same as that for persons, except that vacant units were treated differently. The occupied housing unit ratio estimation procedure was done in four stages, and the vacant housing unit ratio estimation procedure was done in a single stage. The first stage for occupied housing units applied 16 household type categories, while the second stage used the two sampling categories described above for persons. The third stage applied three units-in-building categories, i.e. single units, multiunit less than 10 and multiunit 10 or more. The fourth stage could potentially use 200 tenure/race/Hispanic origin/rent value groups. The stages for ratio estimation for housing units were as follows: OCCUPIED HOUSING UNITS Stage I: Type of Household Group Housing Units With a Family With Own Children Under 18. 1 2 persons in housing unit 2 3 persons in housing unit 3 4 persons in housing unit 4 5 to 7 persons in housing unit 5 9 or more persons in housing unit Housing Units With a Family Without Own Children Under 18. 6-10 2 through 8 or more persons in housing unit All Other Housing Units 11 1 person in housing unit 1 ICPSR 6150 Page 63 12-16 2 persons in housing unit through 8 or more persons in housing unit Stage II: Sampling Rate Category 1 Sampling rate of 1-in-2 2 Sampling rate less than 1-in-2 Stage III: Units in Building 1 Single unit structure 2 Multiunit consisting of fewer than 10 individual units 3 Multiunit consisting of 10 or more individual units Stage IV: Tenure/Race and origin of Householder/ Value of Rent Group Owner White Householder Hispanic origin (Householder) Value of Housing Unit 1 Less than $20,000 2 $20,000 to $39,999 3 $40,000 to $59,999 4 $60,000 to $79,999 5 $80,000 to $99,999 6 $100,000 to $149,999 7 $150,000 to $249,999 8 $250,000 to $299,999 9 $300,000+ 10 Other Householder Not of Hispanic origin 11-20 Same value categories as groups 1 through 10 Black Householder 21-40 Same Hispanic origin/value categories as groups 1 through 20 Asian or Pacific Islander Householder 41-60 Same Hispanic origin/value categories as groups 1 through 20 American Indian, Eskimo, or Aleut 1 Page 64 ICPSR 6150 Householder 61-80 Same Hispanic origin/value categories as groups 1 through 20 Other Race Householder 81-100 Same Hispanic origin/value categories as groups 1 through 20 Renter White Householder Householder of Hispanic origin Group Rent categories 101 Less than $100 102 $100 to $199 103 $200 to $299 104 $300 to $399 105 $400 to $499 106 $500 to $599 107 $600 to $749 108 $750 to $999 109 $1000+ 110 No cash rent Householder Not of Hispanic origin 111-120 Same rent categories as groups 101 through 112 Black Householder 121-140 Same Hispanic origin/rent categories as groups 101 through 120 Asian or Pacific Islander Householder 141-160 Same Hispanic origin/rent origin categories as groups 101 through 120 American Indian, Eskimo, or Aleut Householder 161-180 Same Hispanic origin/rent categories as groups 101 through 120 Other Race Householder 181-200 Same Hispanic origin/rent categories as groups 101 through 120 1 ICPSR 6150 Page 65 VACANT HOUSING UNIT Group 1 Vacant for Rent 2 Vacant for Sale 3 Other Vacant The estimates produced by this procedure realize some of the gains in sampling efficiency that would have resulted if the population had been stratified into the ratio- estimation group before sampling, and the sampling rate had been applied independently to each group. The net effect is a reduction in both the standard error and the possible bias of most estimated characteristic to levels below what would have resulted from simply using the initial (unadjusted) weight. A by-product of this estimation procedure is that the estimates from the sample will for the most part be consistent with the 100-percent figures for the population and housing unit groups used in the estimation procedure. SELECTION OF THE PUBLIC USE MICRODATA SAMPLES A stratified systematic selection procedure with equal probability was used to select each of the public use microdata samples. The sampling universe was defined as all occupied housing units including all occupants, vacant housing units, and GQ persons in the census sample. The sample units were stratified during the selection process. The stratification was intended to improve the reliability of estimates derived from the public use microdata samples by defining strata within which there is a high degree of homogeneity among the census sample households with respect to characteristics of major interest. A total of 1,049 strata were defined; 936 household strata, 104 strata for GQ persons, and 9 strata for vacant housing units. First, the units were divided into three major groups; households, vacant housing units, and GQ population. The household universe was stratified by family type and non-family, race/Hispanic origin of the householder, tenure, and age within sampling stratum. For the census sample selection the population was stratified by geographic size into three sampling strata, i.e., units in small governmental units were sampled at 1-in-2, units in small tract/BNAs were sampled at 1-in-6, and the remainder of the units were sampled at 1-in-8. The vacant housing units universe was stratified by vacancy status and sampling rate. Finally, the GQ population was stratified by GQ type (institutions, non- institutions), race, Hispanic origin, and age. The stratification matrices are defined in tables A, B, and C. 1 Page 66 ICPSR 6150 SUBSAMPLING THE PUMS FILES The sample selection procedures were as follows. The number of 1-percent public use microdata samples for a given state was determined by the full census sample size for that state. For instance, if the full census sample for a state was 20 percent, then the census sample was divided into 20 subsamples of equal size. The 1-percent public use microdata sample was designated at random from the 20 subsamples. From the remaining 19 subsamples, five 1 percent subsamples were designated at random and merged to produce the 5-percent public use microdata sample. The 3-percent elderly public use microdata sample was produced in the same way as the 5-percent but required an extra step. The 3 subsamples were merged and the elderly household and person records, households with at least one person age 60 years or more, or GQ persons 60 years and older, were selected and designated as the elderly PUMS file. During the sample selection operation, consecutive two-digit subsample numbers from 00 to 99 were assigned to each sample case in the 5-percent and 1-percent samples to allow for the designation of various size subsamples and, as discussed in the preceding chapter, to allow for the calculation of standard error. As an example, for a 1-percent public use microdata sample, the choice of records having subsample numbers with the same "units" digit (e.g., the two "units" digit includes subsample numbers (2,12,22,....,92) will provide a 1-in-1000 subsample. Samples of any size between 1/20 and 1/10000 may be selected in a similar manner by using appropriate two-digit subsample numbers assigned to either of the microdata samples. Care must be exercised when selecting such samples. If only one "units" digit is required, the units digit should be randomly selected. If two "units" digits are required, the first should be randomly selected and the second should be either 5 more or 5 less than the first. Failure to use this procedure, e.g., selection of records with the same "tens" digit instead of records with the same "units" digit, would provide a 1-in-10 subsample but one that would be somewhat more clustered and as a result subject to larger sampling error. -------------------- 1. Wolter, Kirk M., Introduction to Variance Estimation, 1985, pp. 55-71. 2. Value of units in this category results from other factors besides housing value alone, for example, inclusion of more than 10 acres of land, or presence of a business establishment on the premises. 1 ICPSR 6150 Page 67 Table A PUMS Stratification Matrix - Households Race & Origin Household/Tenure Household Type Family with Family without Other own children children Household under 18 under 18 (Non-family) Age 0-59 60-74 75-89 90+ White/Other Hispanic Origin Own Rent Non-Hispanic Origin O R CH O R FI O R HA O R KO O R VI O R JA O R AI O R SA O R GU O R OT O 1 Page 68 ICPSR 6150 R Black/American Indian, Eskimo or Aleut O R Repeat for 1-in-6 and 1-in-8 CH - Chinese KO - Korean AI - Asian Indian OT - Other, Asian FI - Filipino VI - Vietnamese SA - Samoan and Pacific HA - Hawaiian JA - Japanese GU - Guamanian Islander O - Owner R - Renter 1 ICPSR 6150 Page 69 Table B: PUMS Stratification Matrix - Vacant Housing Units Sampling Rate 1-in-2 1-in-6 1-in-8 Vacant, for sale Vacant, for rent Vacant, Other Table C: PUMS Stratification Matrix - Group Quarters 0-59 60-74 75-89 90+ GQ Type/Race/Hispanic Origin/Age Institutional/Military White/Other Hispanic Non-Hispanic Black/American Indian/Eskimo or Aleut CH FI HA KO VI JA AI SA GU OT Non-Inst./Non-Military Repea Race/Origin group CH - Chinese KO - Korean AI - Asian Indian OT - Other, Asian FI - Filipino VI - Vietnamese SA - Samoan and Pacific HA - Hawaiian JA - Japanese GU - Guamanian Islander 1 Page 70 ICPSR 6150 - 1 ICPSR 6150 Page 71 CHAPTER 5: RECORD CONTENTS This chapter, in conjunction with several appendices, defines the record layout and applicable codes for the public-use microdata samples. The detailed data dictionary begins on page 5-10 for the housing record and page 5-18 for the person record, with explanatory notes on page C-1 in appendix C. For user convenience, we are providing several indexes which can be used for either PUMS file. Again, the only difference between the files is the PUMA. Note the variable PSA is only applicable to the 3% elderly file--a file which was sponsored by agencies outside the Census Bureau. It contains "Planning Services Areas, identified by the states' health planning agencies. Purchasers of that file will receive a geographic database which equates PSAs to 5% PUMAs if and only if the PSAs match the PUMs. There is no additional geography. Below is an index to the basic data items. The index by character location of the items on the housing and person records follows. In these introductory pages, data fields are specified in the form "H9" or "P12-14," where the letter indicates the Housing or Person record and the numbers indicate the character positions occupied on that record. For example, "P12-14", is a three-character field beginning in character 12 of the person record. in the data dictionary, itself, the "P", or "H" designation appears only at the top of the page, and location is expressed in terms of two separate elements, the beginning location and the size for each mnemonic. The mnemonic is a name for a variable or item. INDEX TO HOUSING ITEMS (BY DESCRIPTION) CHARACTER MNEMONIC LOCATION DESCRIPTION AGSALES H68 1989 sales of agricutlural products AAGSALES H189 1989 sales of agricuLtural products allocation HUSFLAG H41 ALL 100% housing unit data substituted PDSFLAG H42 ALL 100% person data substituted AREATYPE H18-19 Area type BEDROOMS H57 Bedrooms VACANCY3 H54 Boarded up status AVACNCY3 H175 Boarded up status allocation COMMUSE H46 Business or medical office on property ACOMMUSE H170 Business or medical office on property allocation KITCHEN H59 Complete kitchen facilities AKITCHEN H180 Complete kitchen facilities allocation 1 Page 72 ICPSR 6150 PLUMBING H58 Complete plumbing facitities APLUMBNG H179 Complete plumbing facilities allocation ACNDOFEE H202 Condominium fee allocation CONDOFEE H108-111 Condominium fee (monthly amount) DIVISION H10 Division code ELECCOST H69-72 Electricity (yearly cost) AELECCST H190 Electricity (yearly cost) allocation RFAMINC H134-140 Family income RFARM H116 Farm/nonfarm status HFILLER1 H36-38 Filler1 HFILLER2 H87-89 Filler2 HFILLER3 H123 Filler3 AINSAMT H195 Fire, hazard, flood insurance allocation INSAMT H90-93 Fire/hazard/fLood insurance (yearly amount) GASCOST H73-76 Gas (yearly cost) AGASCST H191 Gas (yearly cost) allocation RGRENT H117-120 Gross rent RGRAPI H121-122 Gross rent as a percentage of household income in 1989 GQINST H35 Group quarters institution code FUELHEAT H62 House heating fuel AFUEL H183 House heating fuel allocation FUELCOST H81-84 House heating fuel (yearly cost) ONEACRE H67 House on less than 1 acre AONEACRE H188 House on less than 1 acre allocation CONDO H66 House or apartment part of condominium ACONDO H187 House or apartment part of condominium allocation AFUELCST H193 Household heating fuel (yearly cost) allocation RHHINC H141-147 Household income RHHLANG H149 Household language RHHFAMTP H151-152 Household/famity type SERIALNO H2-8 Housing unit/GQ person serial number HOUSWGT H29-32 Housing weight RLINGISO H150 Linguistic isolation MEALS H51 Meats included in rent AMEALS H173 Meals included in rent allocation AMOBLHME H203 Mobile home costs allocation MOBLHOME H112-115 Mobile home costs (yearly amount) RENT1 H49-50 Monthly rent ARENT1 H172 Monthly rent allocation VACANCY4 H55 Months vacant AVACNCY4 H176 Months vacant allocation MORTGAG3 H95-99 Mortgage payment (monthly amount) MORTGAG H94 Mortgage status AMORTG H196 Mortgage status allocation MSAPMSA H20-23 MSA/PMSA 1 ICPSR 6150 Page 73 ABEDROOM H178 Number of bedrooms allocation RNATADPT H153-154 Number of own natural born/adopted children in household (unweighted) RSTPCHLD H155-156 Number of own stepchildren in household (unweighted) RFAMPERS H157-158 Number of persons in famity (unweighted) PERSONS H33-34 Number of persons records following this housing record RNRLCHLD* H159-160 Number of related children in household (unweighted) ACRE10 H45 On ten acres or more AACRES1 H169 On ten acres or more allocation INSINCL H101 Payment include fire, hazard, flood insurance AINSINCL H199 Payment include fire, hazard, flood insurance allocation TAXINCL H100 Payment include real estate taxes ATAXINCL H198 Payment include real estate taxes allocation PSA H24-26 Planning service area (elderly sample only - state dependent) RNONREL H161 Presence of nonrelatives in household R60OVER H163 Presence of person 60 years and over in household R65OVER H164 Presence of person 65 years and over in household R18UNDR H162 Presence of person under 18 years in household RSUBFAM H165 Presence of subfamilies in household RTAXAMT H85-86 Property taxes (yearly amount) VALUE H47-48 Property value PUMA H13-17 Public Use Microdata Area (state dependent) RECTYPE H1 Record type AMORTG3 H197 Regular mortgage payment allocation ROOMS H43 Rooms AROOMS H167 Rooms allocation SAMPLE H9 Sample identifier MORTGAG2 H102 Second mortgage or home equity loan status AMRTAMT2 H201 Second mortgage payment allocation MORTAMT2 H103-107 Second mortgage payment (monthly amount) AMORTG2 H200 Second mortgage status allocation ROWNRCST H124-128 Selected monthly owner costs RNSMOCPI H129-131 Selected monthly owner costs as a per- centage of household income in 1989 SEWAGE H64 Sewage disposal Revised, June 1993 1 Page 74 ICPSR 6150 ASEWER H185 Sewage disposal allocation WATER H63 Source of water AWATER H184 Source of water allocation RRENTUNT H132 Specified rent unit RVALUNT H133 Specified value unit STATE H11-12 State code SUBSAMPL H27-28 Subsample number (use to pull extracts - 1/1000/etc.) ATAXAMT H194 Taxes on property allocation TELEPHON H60 Telephone in unit APHONE H181 Telephones in unit allocation TENURE H44 Tenure ATENURE H168 Tenure allocation UNITS1 H39-40 Units in structure AUNITS1 H166 Units in structure allocation VACANCY2 H53 Vacancy status AVACNCY2 H174 Vacancy status allocation VACANCY1 H52 Vacant usual home elsewhere (UHE) 1 ICPSR 6150 Page 75 INDEX TO POPULATION ITEMS (BY DESCRIPTION) ENGLISH P71 Ability to speak English AENGLISH P201 Ability to speak English allocation flag AGE P15-16 Age AAGE P187 Age allocation flag AINCOME8 P231 All other income allocation flag INCOME8 P178-182 All other income in 1989 ANCSTRY1 P53-55 Ancestry first entry ANCSTRY2 P56-58 Ancestry second entry AAUGMENT P183 Augmented person AVAIL P113 Available for work AFERTIL P209 Children ever born allocation flag CITIZEN P47 Citizenship ACITIZEN P191 Citizenship allocation flag CLASS P121 Class of worker ACLASS P220 Class of worker allocation AHISPAN P189 Detailed Hispanic origin allocation flag HISPANIC P38-40 Detailed Hispanic origin code ARACE P186 Detailed race allocation flag RACE P12-14 Detailed race code RELAT2 P35 Detailed relationship (other relative) YEARSCH P51-52 Educational attainment REMPLPAR P26-28 Employment status of parents RLABOR P91 Employment status recode ALABOR P210 Employment status recode allocation flag AINCOME3 P226 Farm self-employment income allocation flag INCOME3 P151-156 Farm self-employment income in 1989 (signed) PFILLER2 P81 Filler PFILLER1 P22-25 Filler AANCSTR1 P195 First ancestry allocation flag AYEARSCH P194 Highest education allocation flag HOURS P93-94 Hours worked last week AHOURS P211 Hours worked last week allocation flag SERIALNO P2-8 Housing unit/GQ person serial number INDUSTRY P115-117 Industry AINDUSTR P218 Industry allocation flag INCOME4 P157-162 Interest, dividend, and net rental income AINCOME4 P227 Interest, dividend, and net rental income allocation flag (signed) ALANG1 P199 Language other than English allocation flag LANG1 P67 Language other than English at home LANG2 P68-70 Language spoken at home ALANG2 P200 Language spoken at home allocation flag LOOKING P112 Looking for work MARITAL P17 Marital status AMARITAL P188 Marital status allocation flag RSPOUSE P31 Married, spouse present/spouse absent MEANS P102-103 Means of transportation to work AMEANS P213 Means of transportation to work allocation flag 1 Page 76 ICPSR 6150 MIGPUMA P62-66 Migration PUMA (State dependent) AMIGSTATE P198 Migration State allocation flag MIGSTATE P60-61 Migration State or foreign country code ASERVPER P203 Military periods of service allocation flag MILITARY P72 Military service AVETS1 P202 Military service allocation flag MOBILLIM P87 Mobility limitation AMOBLLIM P207 Mobility limitation status allocation flag AMOBLTY P197 Mobility status allocation flag MOBILITY P59 Mobility status (lived here on April 1, 1985) AINCOME2 P225 Nonfarm self-employment income allocation flag INCOME2 P145-150 Nonfarm self-employment income in 1989 signed FERTIL P89-90 Number of children ever born OCCUP P118-120 Occupation AOCCUP P219 Occupation allocation flag ROWNCHLD P32 Own child POVERTY P41-43 Person poverty status recode PERSCARE P88 Personal care limitation APERCARE P208 Personal care limitation allocation flag PWGT1 P18-21 Person's weight POB P44-46 Place of birth ABIRTHPL P190 Place of birth allocation flag RPOB P29-30 Place of birth recode POWSTATE P95-96 Place of work - State POWPUMA P97-101 Place of work PUMA (state dependent) APOWST P212 Place of work State allocation flag RAGECHLD P33 Presence and age of own children AINCOME6 P229 Public assistance income allocation flag INCOME6 P168-172 Public assistance income in 1989 RECTYPE P1 Record type RRELCHLD P34 Related child RELAT1 P9-10 Relationship ARELAT1 P184 Relationship allocation flag AINCOME7 P230 Retirement income allocation flag INCOME7 P173-177 Retirement income in 1989 SCHOOL P50 School enrollment ASCHOOL P193 School enrollment allocation flag AANCSTR2 P196 Second ancestry allocation flag OTHRSERV P82 Served any other time FEB55 P78 Served February 1955 - July 1964 KOREAN P79 Served Korean conflict (June 1950 - January 1955) MAY75880 P76 Served May 1975 to August 1980 SEPT80 P75 Served September 1980 or later VIETNAM P77 Served Vietnam ERA (August 1964 - April 1975) WWII P80 Served World War II (September 1940 - July 1947) SEX P11 Sex ASEX P185 Sex allocation flag AINCOME5 P228 Social security income allocation flag 1 ICPSR 6150 Page 77 INCOME5 P163-167 Social security income in 1989 SUBFAM2 P36 Subfamily number SUBFAM1 P37 Subfamily relationship TMPABSNT P111 Temporary absence from work DEPART P105-108 Time of departure for work - hour and minute ADEPART P215 Time of departure for work allocation flag REARNING P127-132 Total person's earnings (signed) RPINCOME P133-138 Total person's income (signed) TRAVTIME P109-110 Travel time to work ATRANTME P216 Travel time to work allocation flag AHOUR89 P223 Usual hours worked per week in 1989 allocation HOUR89 P125-126 Usual hours worked per week last year (1989) RIDERS P104 Vehicle occupancy ARIDERS P214 Vehicle occupancy allocation flag RVETSERV P73-74 Veteran period of service AINCOME1 P224 Wages and salary income allocation flag INCOME1 P139-144 Wages or salary income in 1989 (signed) AWKS89 P222 Weeks worked in 1989 allocation flag WEEK89 P123-124 Weeks worked last year (1989) DISABL1 P85 Work limitation status ADISABL1 P205 Work limitation status allocation flag DISABL2 P86 Work prevented status ADISABL2 P206 Work prevention status allocation flag WORKLWK P92 Worked last week AWORK89 P221 Worked last year allocation flag WORK89 P122 Worked last year (1989) YEARWRK P114 Year last worked ALSTWRK P217 Year last worked allocation flag IMMIGR P48-49 Year of entry AIMMIGR P192 Year of entry allocation flag YRSSERV P83-84 Years of active duty military service AYRSSERV P204 Years of military service allocation flag 1 Page 78 ICPSR 6150 INDEX TO HOUSING ITEMS (BY CHARACTER LOCATION) CHARACTER MNEMONIC LOCATION SIZE DESCRIPTION RECTYPE H1 1 Record type SERIALNO H2-8 7 Housing unit/GQ person serial number SAMPLE H9 1 Sample identifier DIVISION H10 1 Division code STATE H11-12 2 State code PUMA H13-17 5 Public use microdata area (state dependent) AREATYPE H18-19 2 Area type MSAPMSA H20-23 4 MSA/PMSA PSA H24-26 3 Planning service area (elderly sample only state dependent) SUBSAMPL H27-28 2 Subsample number (use to pull extracts - 1/1000/etc. HOUSWGT H29-32 4 Housing weight PERSONS H33-34 2 Number of persons records following this housing record GQINST H35 1 Group quarters institution code HFILLER1 H36-38 3 Filler1 UNITS1 H39-40 2 Units in structure HUSFLAG H41 1 All 100% housing unit data substituted PDSFLAG H42 1 All 100% person data substituted ROOMS H43 1 Rooms TENURE H44 1 Tenure ACRE10 H45 1 On ten acres or more COMMUSE H46 1 Business or medical office on property VALUE H47-48 2 Property value RENT1 H49-50 2 Monthly rent MEALS H51 1 Meals included in rent VACANCY1 H52 1 Vacant usual home elsewhere (UHE) VACANCY2 H53 1 Vacancy status VACANCY3 H54 1 Boarded up status VACANCY4 H55 1 Months vacant YRMOVED H56 1 When moved into this house or apartment BEDROOMS H57 1 Bedrooms PLUMBING H58 1 Complete plumbing facilities KITCHEN H59 1 Complete kitchen facilities TELEPHON H60 1 Telephone in unit AUTOS H61 1 Vehicles (1 ton or less) available FUELHEAT H62 1 House heating fuel WATER H63 1 Source of water SEWAGE H64 1 Sewage disposal YRBUILT H65 1 When structure first built CONDO H66 1 House or apartment part of condominium ONEACRE H67 1 House on less than 1 acre AGSALES H68 1 1989 sales of agriculture products ELECCOST H69-72 4 Electricity (yearly cost) 1 ICPSR 6150 Page 79 GASCOST H73-76 4 Gas (yearly cost) WATRCOST H77-80 4 Water (yearly cost) FUELCOST H81-84 4 House heating fuel (yearly cost) RTAXAMT H85-86 2 Property taxes (yearly amount) HFILLER2 H87-89 3 Filler2 INSAMT H90-93 4 Fire/hazard/flood insurance (yearly amount) MORTGAG H94 1 Mortgage status MORTGAG3 H95-99 5 Mortgage payment (monthly amount) TAXINCL H100 1 Payment include real estate taxes INSINCL H101 1 Payment include fire/hazard/flood insurance MORTGAG2 H102 1 Second mortgage or home equity loan status MORTAMT2 H103-107 5 Second mortgage payment (monthly amount) CONDOFEE H108-111 4 Condominium fee (monthly amount) MOBLHOME H112-115 4 Mobile home costs (yearly amount) RFARM H116 1 Farm/nonfarm status RGRENT H117-120 4 Gross rent RGRAPI H121-122 2 Gross rent as a percentage of household income in 1989 HFILLER3 H123 1 Filler3 ROWNCST H124-128 5 Selected monthly owner costs RSMOCPI H129-131 3 Selected monthly owner costs as a percentage of household income in 1989 RRENTUNT H132 1 Specified rent unit RVALUNT H133 1 Specified value unit 1 Page 80 ICPSR 6150 INDEX TO HOUSING ITEMS (BY CHARACTER LOCATION) CON. CHARACTER MNEMONIC LOCATION SIZE DESCRIPTION RFAMINC H134-140 7 Family income RHHINC H141-147 7 Household income RWRKR89 H148 1 Workers in family in 1989 RHHLANG H149 1 Household language RLINGISO H150 2 Linguistic isolation RHHFAMTP H151-152 2 Household/family type RNATADPT H153-154 2 Number of own natural born/adopted children in household (unweighted) RSTPCHLD H155-156 2 Number of own stepchildren in household (unweighted) RFAMPERS H157-158 2 Number of persons in family (unweighted) RNRLCHLD* H159-160 2 Number of related children in household (unweighted) RNONREL H161 1 Presence of nonrelatives in household R18UNDR H162 1 Presence of person under 18 years in household R60OVER H163 1 Presence of person 60 years and over in household R65OVER H164 1 Presence of person 65 years and over in household RSUBFAM H165 1 Presence of subfamilies in household AUNITS1 H166 1 Units in structure allocation AROOMS H167 1 Rooms allocation ATENURE H168 1 Tenure allocation AACRES1 H169 1 On ten acres or more allocation ACOMMUSE H170 1 Business or medical office on property allocation AVALUE H171 1 Value allocation ARENT1 H172 1 Monthly rent allocation AMEALS H173 1 Meats included in rent allocation AVACNCY2 H174 1 Vacancy status allocation AVACNCY3 H175 1 Boarded up status allocation AVACNCY4 H176 1 Months vacant allocation AYRMOVED H177 1 When moved into this house or apartment allocation ABEDROOM H178 1 Number of bedrooms allocation APLUMBNG H179 1 Complete plumbing facilities allocation AKITCHEN H180 1 Complete kitchen facilities allocation APHONE H181 1 Telephones in unit allocation AVEHICLE H182 1 Vehicles available by household allocation AFUEL H183 1 House heating fuel allocation Revised, June 1993 1 ICPSR 6150 Page 81 AWATER H184 1 Source of water allocation ASEWER H185 1 Sewage disposal allocation AYRBUILT H186 1 When structure first built allocation ACONDO H187 1 House or apartment part of condominium allocation AONEACRE H188 1 House on less than 1 acre allocation AAGSALES H189 1 1989 sales of agricuttural products allocation AELECCST H190 1 Etectricity (yearly cost) allocation AGASCST H191 1 Gas (yearly cost) allocation AWATRCST H192 1 Water (yearly cost) allocation AFUELCST H193 1 Household heating fuel (yearly cost) allocation ATAXAMT H194 1 Taxes on property allocation AINSAMT H195 1 Fire, hazard, flood insurance allocation AMORTG H196 1 Mortgage status allocation MORTG3 H197 1 Regular mortgage payment allocation ATAXINCL H198 1 Payment include real estate taxes allocation AINSINCL H199 1 Payment include fire, hazard, flood insurance AMORTG2 H200 1 Second mortgage status allocation AMRTAMT2 H201 1 Second mortgage payment allocation ACNDOFEE H202 1 Condominium fee allocation AMOBLHME H203 1 Mobile home costs allocation FILLER H204-H231 28 Filler 1 Page 82 ICPSR 6150 INDEX TO POPULATION ITEMS (BY CHARACTER LOCATION) CHARACTER MNEMONIC LOCATION SIZE DESCRIPTION RECTYPE P1 1 Record type SERIALNO P2-8 7 Housing unit/GQ person serial number RELAT1 P9-10 2 Relationship SEX P11 1 Sex RACE P12-14 3 Detailed race code AGE P15-16 2 Age MARITAL P17 1 Marital status PWGTl P18-21 4 Person's weight PFILLER1 P22-25 4 Filter REMPLPAR P26-28 3 Employment status of parents RPOB P29-30 2 Place of birth (recode) RSPOUSE P31 1 Married, spouse present/spouse absent ROWNCHLD P32 1 Own child RAGECHLD P33 1 Presence and age of own children RRELCHLD P34 1 Related child RELAT2 P35 1 Detailed relationship (other relative) SUBFAM2 P36 1 Subfamily number SUBFAM1 P37 1 Subfamily relationship HISPANIC P38-40 3 Detailed hispanic origin code POVERTY P41-43 3 Person poverty status recode POB P44-46 3 Place of birth CITIZEN P47 1 Citizenship IMMIGR P48-49 2 Year of entry SCHOOL P50 1 School enrollment YEARSCH P51-52 2 Educational attainment ANCSTRY1 P53-55 3 Ancestry first entry ANCSTRY2 P56-58 3 Ancestry second entry MOBILITY P59 1 Mobility status (lived here on April 1, 1985) MIGSTATE P60-61 2 Migration State or foreign country code MIGPUMA P62-66 5 Migration PUMA (State dependent) LANG1 P67 1 Language other than English at home LANG2 P68-70 3 Language spoken at home ENGLISH P71 1 Ability to speak English MILITARY P72 1 Military service RVETSERV P73-74 2 Veteran period of service SEPT80 P75 1 Served September 1980 or later MAY75880 P76 1 Served May 1975 to August 1980 VIETNAM P77 1 Served Vietnam ERA (August 1964 - April 1975) FEB55 P78 1 Served February 1955 - July 1964 1 ICPSR 6150 Page 83 KOREAN P79 1 Served Korean conflict (June 1950 - January 1955) WWII P80 1 Served World War II (September 1940 - July 1947) PFILLER2 P81 1 Filler OTHRSERV P82 1 Served any other time YRSSERV P83-84 2 Years of active duty military service DISABL1 P85 1 Work limitation status DISABL2 P86 1 Work prevented status MOBILLIM P87 1 Mobility limitation PERSCARE P88 1 Personal care limitation FERTIL P89-90 2 Number of children ever born RLABOR P91 1 Employment status recode WORKLWK P92 1 Worked last week HOURS P93-94 2 Hours worked last week POWSTATE P95-96 2 Place of work - State POWPUMA P97-101 5 Place of work PUMA (State dependent) MEANS P102-103 2 Means of transportation to work RIDERS P104 1 Vehicle occupancy DEPART P105-108 4 Time of departure for work - hour and minute TRAVTIME P109-110 2 Travel time to work TMPABSNT P111 1 Temporary absence from work COOKING P112 1 Looking for work AVAIL P113 1 Available for work YEARWRK P114 1 Year last worked INDUSTRY P115-117 3 Industry OCCUP P118-120 3 Occupation 1 Page 84 ICPSR 6150 - 1 ICPSR 6150 Page 85 1990 PUBLIC USE MICRODATA SAMPLES, U.S. DATA DICTIONARY HOUSING UNIT RECORD DATA SIZE BEGIN D RECTYPE 1 1 Record Type V H .Housing Record D SERIALNO 7 2 V 0000000.. 9999999 .Housing unit/GQ person serial number unique .identifier assigned within state or state group D SAMPLE 1 9 Sample Identifier V 1 .5% sample V 2 .1% sample V 3 .Elderly D DIVISION 1 10 Division code V 0 .Region/division not identifiable V .(Selected MSA/PMSAs on 1% sample) V 1 .New England (Northeast region) V 2 .Middle Atlantic (Northeast region) V 3 .East North Central (Midwest region) V 4 .West North Central (Midwest region) V 5 .South Atlantic (South region) V 6 .East South Central (South region) V 7 .West South Central (South Region) V 8 .Mountain (West region) V 9 .Pacific (West region) D STATE 2 11 State Code V 01..56 .FIPS state code (See appendix I) V 99 .PUMA boundaries cross state lines - 1% file D PUMA 5 13 Public use microdata area (state dependent) V 00100.. V 99999 .PUMA code (Includes tract groups) 1st 3 V .Digits = main PUMA - generally county place V .Last 2 digits = groups of tracts, BNA, etc. 1 Page 86 ICPSR 6150 D AREATYPE 2 18 Area type revised for PUMS equivalency file V 10 .Central city V 11 .Central city part V 20 .MSA/PMSA - Outside central city V 21 .MSA/PMSA - Outside central city (part) V 22 .Central City (part) & outside central city V .(part) V 30 .Entire MSA V 31 .2 or more MSAs/PMSAs V 40 .Mixed MSA/PMSA/NON-MSA/PMSA area V 50 .Outside MSA/PMSA V 60 .Place V 61 .Place - part V 70 .MCDs/Towns (New England only) V 80 .Counties/independent Cities (2 or more) V 81 .County/independent city - part V 82 .County/independent city D MSAPMSA 4 20 MSA/PMSA V 0040.. V 9340 .FIPS/MSA/PMSA code, selected MSA/PMSA V .(See appendix G) V 9997 .Mixed MSA/PMSA NONMSA/PMSA area V 9998 .2 or more MSAs V 9999 .Not in MA D PSA 3 24 Planning service area (elderly sample only - state dependent) V 000 .N/A (Elderly PUMS only) V 1..18B .Planning service area codes (See appendix G) D SUBSAMPL 2 27 Subsample number (Use to pull extracts - 1/1000/etc.) V 00..99 .See text. pp 4-45. D HOUSWGT 4 29 Housing Weight V 0000.. V 1152 .Integer weight of housing unit D PERSONS 2 33 Number of person records following this housing record V 00 .Vacant unit V 01 .One person record (one person in household V .or any person in group quarters) V 02..29 .Number of person records (number of persons V .in household) 1 ICPSR 6150 Page 87 D GQINST 1 35 Group quarters institution V 0 .N/A (housing unit) V 1 .Institutionalized V 2 .Not institutionalized D HFILLER 3 36 Filler D UNITS1 2 39 Units in structure V 00 .N/A (GQ) V 01 .Mobile home or trailer V 02 .One-family house detached V 03 .One-family house attached V 04 .2 Apartments V 05 .3-4 Apartments V 06 .5-9 Apartments V 07 .10-19 Apartments V 08 .20-49 Apartments V 09 .50 or more apartments V 10 .Other D HUSFLAG 1 41 All 100% housing unit data substituted V 0 .No V 1 .Yes D PDSFLAG 1 42 All 100% person data substituted V 0 .No V 1 .Yes D ROOMS 1 43 Rooms V 0 .N/A (GQ) V 1 .1 Room V 2 .2 Rooms V 3 .3 Rooms V 4 .4 Rooms V 5 .5 Rooms V 6 .6 Rooms V 7 .7 Rooms V 8 .8 Rooms V 9 .9 or more rooms D TENURE 1 44 Tenure V 0 .N/A (GQ/vacant) 1 Page 88 ICPSR 6150 V 1 .Owned with mortgage or loan V 2 .Owned free and clear V 3 .Rented for cash rent V 4 .No cash rent D ACRE10 1 45 On ten acres or more V 0 .N/A (GQ/not a one-family house or mobile home) V 1 .House on ten or more acres V 2 .House on less than ten acres D COMMUSE 1 46 Business or medical office on property V 0 .N/A (GQ/not a one-family house or mobile home) 1 .Yes V 2 .No D VALUE 2 47 Property value V 00 .N/A (GQ/rental unit/vacant, not for sale only) V 01 .Less than $ 10000 02 .$ 10000 - $ 14999 V 03 .$ 15000 - $ 19999 V 04 .$ 20000 - $ 24999 V 05 .$ 25000 - $ 29999 V 06 .$ 30000 - $ 34999 V 07 .$ 35000 - $ 39999 V 08 .$ 40000 - $ 44999 V 09 .$ 45000 - $ 49999 V 10 .$ 50000 - $ 54999 V 11 .$ 55000 - $ 59999 V 12 .$ 60000 - $ 64999 V 13 .$ 65000 - $ 69999 V 14 .$ 70000 - $ 74999 V 15 .$ 75000 - $ 79999 V 16 .$ 80000 - $ 89999 V 17 .$ 90000 - $ 99999 V 18 .$100000 - $124999 V 19 .$125000 - $149999 V 20 .$150000 - $174999 V 21 .$175000 - $199999 V 22 .$200000 - $249999 V 23 .$250000 - $299999 V 24 .$300000 - $399999 V 25 .$400000 or more D RENT1 2 49 Monthly rent V 00 .N/A (GQ/not a rental unit) 1 ICPSR 6150 Page 89 V 01 .Less than $ 80 V 02 .$ 80 - $ 99 V 03 .$ 100 - $124 V 04 .$ 125 - $149 V 05 .$ 150 - $174 V 06 .$ 175 - $199 V 07 .$ 200 - $224 V 08 .$ 225 - $249 V 09 .$ 250 - $274 V 10 .$ 275 - $299 V 11 .$ 300 - $324 V 12 .$ 325 - $349 V 13 .$ 350 - $374 V 14 .$ 375 - $399 V 15 .$ 400 - $424 V 16 .$ 425 - $449 V 17 .$ 450 - $474 V 18 .$ 475 - $499 V 19 .$ 500 - $524 V 20 .$ 525 - $549 V 21 .$ 550 - $599 V 22 .$ 600 - $649 V 23 .$ 650 - $699 V 24 .$ 700 - $749 V 25 .$ 750 - $999 V 26 .$1000 or more V 27 .No cash rent (NCR) D MEALS 1 51 Meals included in rent V 0 .N/A (GQ/not a rental unit/rental-NCR) V 1 .Yes V 2 .No D VACANCY1 1 52 Vacant usual home elsewhere (UHE) V 0 .N/A (occupied or regular vacant/GQ) V 1 .Vacant UHE-owner V 2 .Vacant UHE-renter V 3 .Vacant UHE-undetermined D VACANCY2 1 53 Vacancy status V 0 .N/A (occupied/GQ) V 1 .For rent V 2 .For sale only V 3 .Rented or sold, not occupied V 4 .For seasonal/recreational/occasional use V 5 .For migratory workers 1 Page 90 ICPSR 6150 V 6 .Other vacant D VACANCY3 1 54 Boarded up status V 0 .N/A (occupied/GQ) V 1 .Yes V 2 .No D VACANCY4 1 55 Months vacant V 0 .N/A (occupied/GQ) V 1 .Less than 1 month V 2 .1 up to 2 months V 3 .2 up to 6 months V 4 .6 up to 12 months V 5 .12 up to 24 months V 6 .24 or more months D YRMOVED 1 56 When moved into this house or apartment V 0 .N/A (GQ/vacant) V 1 .1989 or 1990 V 2 .1985 to 1988 V 3 .1980 to 1984 V 4 .1970 to 1979 V 5 .1960 to 1969 V 6 .1959 or earlier D BEDROOMS 1 57 Bedrooms V 0 .N/A (GQ) V 1 .No bedrooms V 2 .1 Bedroom V 3 .2 Bedrooms V 4 .3 Bedrooms V 5 .4 Bedrooms V 6 .5 or more bedrooms D PLUMBING 1 58 Complete plumbing facilities V 0 .N/A (GQ) V 1 .Yes, all three facilities V 2 .No D KITCHEN 1 59 Complete kitchen facilities V 0 .N/A (GQ) V 1 .Yes V 2 .No 1 ICPSR 6150 Page 91 D TELEPHON 1 60 Telephone in Unit V 0 .N/A (GQ/vacant) V 1 .Yes V 2 .No D AUTOS 1 61 Vehicles (1 ton or less) available V 0 .N/A (GQ/vacant) V 1 .No vehicles V 2 .1 vehicle V 3 .2 vehicles V 4 .3 vehicles V 5 .4 Vehicles V 6 .5 Vehicles V 7 .6 Vehicles V 8 .7 or more vehicles D FUELHEAT 1 62 House heating fuel V 0 .N/A (GQ/vacant) V 1 .Gas: Underground pipes V 2 .Gas: Bottled, tank, or LP V 3 .Electricity V 4 .Fuel oil, kerosene, etc. V 5 .Coal or coke V 6 .Wood V 7 .Solar energy V 8 .Other fuel V 9 .No fuel used D WATER 1 63 Source of water V 0 .N/A (GQ) V 1 .Public system or private company V 2 .Individual drilled well V 3 .Individual dug well V 4 .Other source such as a spring, creek, etc. D SEWAGE 1 64 Sewage disposal V 0 .N/A (GQ) V 1 .Public sewer V 2 .Septic tank or cesspool V 3 .Other means D YRBUILT 1 65 When structure first built V 0 .N/A (GQ) 1 Page 92 ICPSR 6150 V 1 .1989 or 1990 V 2 .1985 to 1988 V 3 .1980 to 1984 V 4 .1970 to 1979 V 5 .1960 to 1969 V 6 .1950 to 1959 V 7 .1940 to 1949 V 8 .1939 or earlier D CONDO 1 66 House or apartment part of condominium V 0 .N/A (GQ) V 1 .Yes V 2 .No D ONEACRE 1 67 House on less than 1 acre V 0 .N/A (GQ, two or more units in structure) V 1 .Yes V 2 .No D AGSALES 1 68 1989 Sales of Agriculture Products V 0 .N/A (less than 1 acre/GQ/vacant/ V .2 or more units in structure) V 1 .None V 2 .$1 to $999 V 3 .$1,000 to $2,499 V 4 .$2,500 to $4,999 V 5 .$5,000 to $9,999 V 6 .$10,000 or more D ELECCOST 4 69 Electricity (yearly cost)* V 0000 .N/A (GQ/vacant) V 0001 .Included in rent or in condo fee V 0002 .No charge or electricity not used V 0003.. 3099 .$3 to $3,099 V 3100 .Topcode V 3101+ .$3101 or more = state median of topcoded .values D GASCOST 4 73 Gas (yearly cost)* V 0000 .N/A (GQ/vacant) V 0001 .Included in rent or in condo fee V 0002 .No charge or gas not used 1 ICPSR 6150 Page 93 V 0003.. 2099 .$3 to $2,099 V 2100 .Topcode V 2101+ .$2101 or more = state median of topcoded .values D WATRCOST 4 77 Water (yearly cost) V 000 .N/A (GQ/vacant) V 001 .Included in rent or in condo fee V 002 .No charge V 003..999 .$3 to $999 V 1000 .Topcode V 1000+ .$1001+ or more = state median of topcoded .values D FUELCOST 4 81 House heating fuel (yearly cost) V 0000 .N/A (GQ/vacant) V 0001 .Included in rent or in condo fee V 0002 .No charge or these fuels not used V 0003.. 1899 .$3 to $1,899 V 1900 .Topcode V 1,901+ .$1,901 or more = state median of topcoded .value D RTAXAMT 2 85 Property taxes (yearly amount) V 00 .N/A (GQ/vacant/not owned or being bought/not a .one-family house, mobile home or trailer or .condo) V 01 .None V 02 .$ 2 - $ 49 V 03 .$ 50 - $ 99 V 04 .$ 100 - $ 149 V 05 .$ 150 - $ 199 V 06 .$ 200 - $ 249 V 07 .$ 250 - $ 299 V 08 .$ 300 - $ 349 V 09 .$ 350 - $ 399 V 10 .$ 400 - $ 449 V 11 .$ 450 - $ 499 V 12 .$ 500 - $ 549 V 13 .$ 550 - $ 599 V 14 .$ 600 - $ 649 V 15 .$ 650 - $ 699 V 16 .$ 700 - $ 749 V 17 .$ 750 - $ 799 1 Page 94 ICPSR 6150 V 18 .$ 800 - $ 849 V 19 .$ 850 - $ 899 V 20 .$ 900 - $ 949 V 21 .$ 950 - $ 999 V 22 .$1000 - $1099 V 23 .$1100 - $1199 V 24 .$1200 - $1299 V 25 .$1300 - $1399 V 26 .$1400 - $1499 V 27 .$1500 - $1599 V 28 .$1600 - $1699 V 29 .$1700 - $1799 V 30 .$1800 - $1899 V 31 .$1900 - $1999 V 32 .$2000 - $2099 V 33 .$2100 - $2199 V 34 .$2200 - $2299 V 35 .$2300 - $2399 V 36 .$2400 - $2499 V 37 .$2500 - $2599 V 38 .$2600 - $2699 V 39 .$2700 - $2799 V 40 .$2800 - $2899 V 41 .$2900 - $2999 V 42 .$3000 - $3099 V 43 .$3100 - $3199 V 44 .$3200 - $3299 V 45 .$3300 - $3399 V 46 .$3400 - $3499 V 47 .$3500 - $3599 V 48 .$3600 - $3699 V 49 .$3700 - $3799 V 50 .$3800 - $3899 V 51 .$3900 - $3999 V 52 .$4000 - $4099 V 53 .$4100 - $4199 V 54 .$4200 - $4299 V 55 .$4300 - $4399 V 56 .$4400 - $4499 V 57 .$4500 = Topcode V 58 .$4501 - $5499~D?RANGE V 59 .$5500 - $7499 3 FOR V 60 .$7500 or more~DY MEDIAN D HFILLER2 3 87 D INSAMT 4 90 Fire/hazard/flood insurance (yearly amount) 1 ICPSR 6150 Page 95 V 0000 .N/A (not owned or being bought/not a one V .family house, mobile home, or condo/GQ/vacant) V 0001 .None V 0002.. 1299 .$2 to $1,299 V 1300 .Topcode V 1301+ .$1,301 or more=state median of topcoded values D MORTGAG 1 94 Mortgage status V 0 .N/A (not owned or being bought/not a one family .house, mobile home, or condo/GQ/vacant) V 1 .Mortgage deed of trust, or similar debt V 2 .Contract to purchase V 3 .None D MORTGAG3 5 95 Mortgage payment (monthly amount) V 00000 .N/A (not owned or being bought/not a one .family house, mobile home, or condo/GQ/vacant) V 00001 .No regular payment required V 00002.. 01999 .$2 to $1,999 V 02000 .Topcode V 02001+ .$2,001 or more = state median of topcoded .values D TAXINCL 1 100 Payment include real estate taxes V 0 .N/A (GQ/vacant/not owned or being bought/ .not a one family house or condo/not mortgaged/ .No regular mortgage payment) V 1 .Yes, taxes included in payment V 2 .No, taxes paid separately or taxes not required D INSINCL 1 101 Payment include fire/hazard/flood insurance V 0 .N/A (GQ/vacant/not owned or being bought/ .Not a one family house, MHT or condo/not .mortgaged/no regular mortgage payment) V 1 .Yes, insurance included in payment V 2 .No, insurance paid separately or no insurance D MORTGAG2 1 102 Second mortgage or home equity loan status V 0 .N/A (GQ/vacant/not owned or being bought/ .not a one family house, mobile home, trailer or .condo/not mortgaged/no second mortgage) V 1 .Yes V 2 .No 1 Page 96 ICPSR 6150 D MORTAMT2 5 103 Second mortgage payment (monthly amount) V 00000 .N/A (GQ/vacant/condo/not owned or being .bought/not a one family house/not mortgaged/ .no second mortgage) V 00001 .No regular payment required V 00002.. 00999 .$2 to $999 V 01000 .Topcode V 01001+ .$1001 or more = state median of topcoded .values D CONDOFEE 4 108 Condo fee (monthly amount) V 0000 .N/A (not owned or being bought/not V .condo/GQ/vacant/no condo fee) V 0001.. 0599 .$1 - $599 V 0600 .Topcode V 0601+ .$601 or more = state median of topcoded values D MOBLHOME 4 112 Mobile home costs (yearly amount) V 0000 .N/A (GQ/vacant/not owned or being bought/ .not mobile home/no costs) V 0001.. V 3399 .$1 - $3,399 (cost in dollars) V 3400 .Topcode V 3401+ .$3401 or more = state median of topcoded V .values D RFARM 1 116 Farm/nonfarm status V 0 .N/A (urban) V 1 .Rural farm V 2 .Rural nonfarm D RGRENT 4 117 Gross rent V 0000 .N/A (GQ/vacant, not rented for cash rent) V 0001.. 1499 .Gross rent (dollars) V 1500 .Topcode V 1501+ .1501 or more = state median of topcoded values D RGRAPI 2 121 Gross rent as a percentage of household income in 1989 V 00 .N/A (GQ/vacant/not rented for cash rent/owner .occupied/no household income) 1 ICPSR 6150 Page 97 V 01 . 1% to 9% V 02 .10% to 14% V 03 .15% to 19% V 04 .20% to 24% V 05 .25% to 29% V 06 .30% to 34% V 07 .35% to 39% V 08 .40% to 49% V 09 .50% to 59% V 10 .60% to 69% V 11 .70% to 79% V 12 .80% to 89% V 13 .90% to 99% V 14 .100% or more D HFILLER3 1 123 Filler D ROWNRCST 5 124 Selected monthly owner costs V 00000 .N/A (not owned or being bought/not a one V .family house, mobile home, or V .condo/GQ/vacant/no costs ) V 00001.. 20299 .Monthly owner costs in dollars V 20300 .Topcode D RNSMOCPI 3 129 Selected monthly owner costs as a percentage of household income in 1989 V 000 .N/A (not owned or being bought/not a one family .house, mobile home, or condo/GQ/vacant/no HH .income) V 001..100 .1% to 100% V 101 .101% or more D RRENTUNT 1 132 Specified rent unit V 0 .Not specified rent unit V 1 .Specified rent unit D RVALUNT 1 133 Specified value unit V 0 .Not specified value unit V 1 .Specified value unit D RFAMINC 7 134 Family income V 0000000 .N/A(GQ/vacant/no income) 1 Page 98 ICPSR 6150 V -999999.. V 9999999 .Total family income in dollars (See user notes .for state maximum and minimum values) D RHHINC 7 141 Household income V 0000000 .N/A(GQ/vacant/no income) V -999999.. 9999999 .Total household income in dollars (See user notes .for state maximum and minimum values) D RWRKR89 1 148 Workers in family in 1989 V 0 .N/A (GQ/vacant/non-family household) V 1 .No workers V 2 .1 worker V 3 .2 workers V 4 .3 or more workers in family D RHHLANG 1 149 Household language V 0 .N/A (GQ/vacant) V 1 .English only V 2 .Spanish V 3 .Other Indo-European language V 4 .Asian or Pacific Island language V 5 .Other language D RLINGISO 1 150 Linguistic isolation V 0 .N/A (GQ/vacant) V 1 .Not linguistically isolated V 2 .Linguistically isolated D RHHFAMTP 2 151 Household/family type V 00 .N/A (GQ/vacant) V 01 .Married-couple family household V Other family household: V 02 .Male householder V 03 .Female householder V Nonfamily household: V Male householder: V 11 .Living alone V 12 .Not living alone V Female householder: V 21 .Living alone V 22 .Not living alone 1 ICPSR 6150 Page 99 D RNATADPT 2 153 Number of own natural born/adopted children in household (unweighted) V 00 .N/A(GQ/vacant/no own natural born/adopted V .children) V 01..28 .Number of own children natural born/adopted .children in household D RSTPCHLD 2 155 Number of own stepchildren in household (unweighted) V 00 .N/A(GQ/vacant/no own stepchildren) V 01..28 .Number of own stepchildren in household D RFAMPERS 2 157 Number of persons in family (unweighted) V 00 .N/A (GQ/vacant/non-family household) V 01..29 .Number of persons in family D RNRLCHLD* 2 159 Number of related children in household (unweighted) V 00 .N/A (GQ/vacant/no related children) V 01..28 .Number of related children in household D RNONREL 1 161 Presence of nonrelatives in household V 0 .N/A (No nonrelatives in household/GQ/vacant) V 1 .1 or more nonrelatives in household D R18UNDR 1 162 Presence of person under 18 years in household V 0 .N/A (No person under 18 in household/GQ/vacant) V 1 .1 or more person under 18 in household D R60OVER 1 163 Presence of persons 60 years and over in household V 0 .N/A (No person 60 and over/GQ/vacant) V 1 .1 person 60 and over (unweighted) V 2 .2 or more person 60 and over (unweighted) D R65OVER 1 164 Presence of person 65 years and over in household V 0 .N/A (No person 65 and over/GQ/vacant) V 1 .1 person 65 and over (unweighted) V 2 .2 or more person 65 and over (unweighted) D RSUBFAM 1 165 Presence of subfamilies in Household V 0 .N/A (No subfamilies or not V .applicable/GQ/vacant) Revised, June 1993 1 Page 100 ICPSR 6150 V 1 .1 or more subfamilies D AUNITS1 1 166 Units in structure allocation V 0 .No V 1 .Yes D AROOMS 1 167 Rooms allocation V 0 .No V 1 .Yes D ATENURE 1 168 Tenure allocation V 0 .No V 1 .Yes D AACRES1 1 169 On ten acres or more allocation V 0 .No V 1 .Yes D ACOMMUSE 1 170 Business or medical office on property allocation V 0 .No V 1 .Yes D AVALUE 1 171 Value allocation V 0 .No V 1 .Yes D ARENT1 1 172 Monthly rent allocation V 0 .No V 1 .Yes D AMEALS 1 173 Meals included in rent allocation V 0 .No V 1 .Yes D AVACNCY2 1 174 Vacancy status allocation V 0 .No V 1 .Yes D AVACNCY3 1 175 Boarded up status allocation 1 ICPSR 6150 Page 101 V 0 .No V 1 .Yes D AVACNCY4 1 176 Months vacant allocation V 0 .No V 1 .Yes D AYRMOVED 1 177 When moved into this house or apartment allocation V 0 .No V 1 .Yes D ABEDROOM 1 178 Number of bedrooms allocation V 0 .No V 1 .Yes D APLUMBNG 1 179 Complete plumbing facilities allocation V 0 .No V 1 .Yes D AKITCHEN 1 180 Complete kitchen facilities allocation V 0 .No V 1 .Yes D APHONE 1 181 Telephones in house allocation V 0 .No V 1 .Yes D AVEHICLE 1 182 Vehicles available by household allocation V 0 .No V 1 .Yes D AFUEL 1 183 House heating fuel allocation V 0 .No V 1 .Yes D AWATER 1 184 Source of water allocation V 0 .No V 1 .Yes 1 Page 102 ICPSR 6150 D ASEWER 1 185 Sewage disposal allocation V 0 .No V 1 .Yes D AYRBUILT 1 186 When structure first built allocation V 0 .No V 1 .Yes from not answered V 2 .Yes "don't know" D ACONDO 1 187 House or apartment part of condominium allocation V 0 .No V 1 .Yes D AONEACRE 1 188 House on less than 1 acre allocation V 0 .No V 1 .Yes D AAGSALES 1 189 1989 Sales of Agricultural Products allocation V 0 .No V 1 .Yes D AELECCST 1 190 Electricity (yearly cost) allocation V 0 .No V 1 .Yes D AGASCST 1 191 Gas (yearly cost) allocation V 0 .No V 1 .Yes D AWATRCST 1 192 Water (yearly cost) allocation V 0 .No V 1 .Yes D AFUELCST* 1 193 House heating fuel (yearly cost) allocation V 0 .No V 1 .Yes D ATAXAMT 1 194 Taxes on property allocation Revised, June 1993 1 ICPSR 6150 Page 103 V 0 .No V 1 .Yes D AINSAMT 1 195 Fire, hazard, flood insurance allocation V 0 .No V 1 .Yes D AMORTG 1 196 Mortgage status allocation V 0 .No V 1 .Yes no answer V 2 .Yes from junior mortgage D AMORTG3 1 197 Regular mortgage payment allocation V 0 .No V 1 .Yes D ATAXINCL 1 198 Payment include real estate taxes allocation V 0 .No V 1 .Yes D AINSINCL 1 199 Payment include fire, hazard, flood insurance allocation V 0 .No V 1 .Yes D AMORTG2 1 200 Second mortgage status allocation V 0 .No V 1 .Yes D AMRTAMT2 1 201 Second mortgage payment allocation V 0 .NO V 1 .Yes D ACNDOFEE 1 202 Condominium fee allocation V 0 .No V 1 .Yes 1 Page 104 ICPSR 6150 D AMOBLHME 1 203 Mobile home costs allocation V 0 .No V 1 .Yes D FILLER 28 204 1 ICPSR 6150 Page 105 1990 PUBLIC USE MICRODATA SAMPLES, U.S. DATA DICTIONARY PERSON RECORD DATA SIZE BEGIN D RECTYPE 1 1 Record Type V P .Person Record D SERIALNO 7 2 V 0000000.. V 9999999 .Housing unit/GQ person serial number unique V .identifier assigned within state or state group D RELAT1 2 9 Relationship V 00 .Householder V 01 .Husband/wife V 02 .Son/daughter V 03 .Stepson/stepdaughter V 04 .Brother/sister V 05 .Father/mother V 06 .Grandchild V 07 .Other relative Not related V 08 .Roomer/boarder/foster child V 09 .Housemate/roommate V 10 .Unmarried partner V 11 .Other nonrelative Group quarters V 12 .Institutionalized person V 13 .Other persons in group quarters D SEX 1 11 Sex V 0 .Male V 1 .Female D RACE 3 12 Recoded detailed race code (Appendix C) V 001-037 .(See appendix C) V 301-327 .American Indian Tribes D AGE 2 15 Age V 00 .Less than 1 year 1 Page 106 ICPSR 6150 V 01..89 .Age in years V 90 .90 or more years old D MARITAL 1 17 Marital status V 0 .Now married, except separated V 1 .Widowed V 2 .Divorced V 3 .Separated V 4 .Never married or under 15 years old D PWGT1 4 18 Person's weight V * 0000.. V 1152 .Person's weight D PFILLER1 4 22 Filler D REMPLPAR 3 26 Employment status of parents V 000 .N/A (not own child of householder, and not .child in subfamily) V Living with two parents: V Both parents in labor force: V 111 .Both parents at work 35 or more hours V 112 .Father only at work 35 or more hours V 113 .Mother only at work 35 or more hours V 114 .Neither parent at work 35 or more hours V Father only in labor force: V 121 .Father at work 35 or more hours V 122 .Father not at work 35 or more hours V Mother only in labor force: V 133 .Mother at work 35 or more hours V 134 .Mother not at work 35 or more hours V 141 Neither parent in labor force V Living with one parent: V Living with father: V 211 .Father at work 35 or more hours V 212 .Father not at work 35 or more hours V 213 .Father not in labor force V Living with mother: V 221 .Mother at work 35 or more hours V 222 .Mother not at work 35 or more hours V 223 .Mother not in labor force Revised, June 1993 1 ICPSR 6150 Page 107 D RPOB 2 29 Place of birth (Recode) V 10 .Born in State of residence V Born in other State in the U.S.: V 21 .Northeast V 22 .Midwest V 23 .South V 24 .West V U.S. outlying areas: V 31 .Puerto Rico V 32 .American Samoa V 33 .Guam V 34 .Northern Marianas V 35 .US Virgin Islands V 36 .Elsewhere V 40 .Born abroad of American parents V Foreign born: V 51 .Naturalized citizen V 52 .Not a citizen D RSPOUSE 1 31 Married, spouse present/spouse absent V 0 .N/A (less than 15 years old) V 1 .Now married, spouse present V 2 .Now married, spouse absent V 3 .Widowed V 4 .Divorced V 5 .Separated V 6 .Never married D ROWNCHLD 1 32 *Own child (See Appendix B) V * 1 .Own child V * 0 .Not own child D RAGECHLD 1 33 Presence and age of own children V * 0 .N/A (male) V 1 .With own children under 6 years only V 2 .With own children 6 to 17 years only V 3 .With own children under 6 years and 6 to 17 .years V * 4 .No own children (.incl. females under 16 years) D RRELCHLD 1 34 *Related child (See Appendix B) V * 1 .Related child V * 0 .Not related child Revised, June 1993 1 Page 108 ICPSR 6150 D RELAT2 1 35 Detailed relationship (other relative) V 0 .N/A (GQ/not other relative) V 1 .Son-in-law/daughter-in-law V 2 .Father-in-law/mother-in-law V 3 .Brother-in-law/sister-in-law V 4 .Nephew/niece V 5 .Grandparent V 6 .Uncle/aunt V 7 .Cousin V 8 .Other related by blood or marriage V 9 .Other relative D SUBFAM2 1 36 Subfamily number V 0 .N/A (GQ/not in a subfamily) V 1 .In subfamily 1 V 2 .In subfamily 2 V 3 .In subfamily 3 D SUBFAM1 1 37 Subfamily relationship V 0 .N/A (GQ/not in a subfamily) V 1 .Husband/wife V 2 .Parent in a parent/child subfamily V 3 .Child in subfamily D HISPANIC 3 38 Detailed Hispanic origin code (See appendix I) V 000,006.. . 199 .Not hispanic V 001,210.. 220 .Mexican, mex-am V 002,261.. 270 .Puerto Rican V 003,271.. 274 .Cuban V 221..230 .Central American V 231..249 .South American V 275..289 .Dominican V 004,200.. 209,250.. 260 V 290..401 .Other Hispanic D POVERTY 3 41 Person poverty status recode (See appendix B) V 000 .N/A 1 ICPSR 6150 Page 109 V 001..500 .% Below or above poverty status value V 501 .501% or more of poverty value D POB 3 44 Place of birth (Appendix I) V 001..056 .FIPS State code (U.S. States and D.C.) V 060..099 .Puerto Rico (072) or U.S. outlying area V 100..553 .Foreign country V 554 .At sea V 555 .Abroad, not specified D CITIZEN 1 47 Citizenship V 0 .Born in the U.S. V 1 .Born in Puerto Rico, Guam, and outlying areas V 2 .Born abroad of American parents V 3 .U.S. citizen by naturalization V 4 .Not a citizen of the U.S D IMMIGR 2 48 Year of entry V 00 .Born in the U.S. V 01 .1987 to 1990 V 02 .1985 to 1986 V 03 .1982 to 1984 V 04 .1980 or 1981 V 05 .1975 to 1979 V 06 .1970 to 1974 V 07 .1965 to 1969 V 08 .1960 to 1964 V 09 .1950 to 1959 V 10 .Before 1950 D SCHOOL 1 50 School enrollment V 0 .N/A (less than 3 years old) V 1 .Not attending school V 2 .Yes, public school, public college V 3 .Yes, private school, private college D YEARSCH 2 51 Educational attainment V 00 .N/A (less than 3 years old) V 01 .No school completed V 02 .Nursery school V 03 .Kindergarten V 04 .1st, 2nd, 3rd, or 4th grade 1 Page 110 ICPSR 6150 V 05 .5th, 6th, 7th, or 8th grade V 06 .9th grade V 07 .10th grade V 08 .11th grade V 09 .12th grade, no diploma V 10 .High school graduate, diploma or GED V 11 .Some college, but no degree V 12 .Associate degree in college, occupational program V 13 .Associate degree in college, academic program V 14 .Bachelor's degree V 15 .Master's degree V 16 .Professional degree V 17 .Doctorate degree D ANCSTRY1 3 53 Ancestry - first entry (See appendix I) V 001..998 .Ancestry codes - first entry V 999 .Not reported D ANCSTRY2 3 56 Ancestry - second entry (See appendix I) V 000 .No secondary ancestry V 001..998 .Ancestry codes V 999 .Not reported D MOBILITY 1 59 Mobility status (lived here on April 1, 1985) V 0 .N/A(vacant/less than 5 years old) V 1 .Yes, same house (nonmovers) V 2 .No, different house (movers) D MIGSTATE 2 60 Migration - State or foreign country code (Appendix I) V 00 .N/A (person less than 5 years old/lived V .in same house in 1985) V 01..56 .FIPS state code (U.S. States and D.C.) V 72 .Puerto Rico V 98 .Other abroad in 1985 V 99 .State not identified (B sample) D MIGPUMA 5 62 Migration PUMA (state dependent) V 00000 .N/A (person less than 5 years old/lived in .same house in 1985) V 00100.. 99800 .Migration PUMA * (Not coded to tract level) V 99900 .Abroad Revised, June 1993 1 ICPSR 6150 Page 111 D LANG1 1 67 Language other than English at home V 0 .N/A (less than 5 years old) V 1 .Yes, speaks another language V 2 .No, speaks only English D LANG2 3 68 Language spoken at home (See appendix I) V 000..600 .N/A (less than 5 years old/speaks only .English) V 601..999 .Specific language codes D ENGLISH 1 71 Ability to speak English V 0 .N/A (less than 5 years old/speaks only English) V 1 .Very well V 2 .Well V 3 .Not well V 4 .Not at all D MILITARY 1 72 Military service V 0 .N/A (less than 16 years old) V 1 .Yes, now on active duty V 2 .Yes, on active duty in past, but not now V 3 .Yes, service in reserves or national guard only V 4 .No service D RVETSERV 2 73 Veteran period of service V 00 .N/A (less than 16 years old, no active duty) V 01 .September 1980 or later only V 02 .May 1975 to August 1980 only V 03 .May 1975 to August 1980 and September 1980 V .or later only V 04 .Vietnam era, no Korean conflict, no WWII V 05 .Vietnam era and Korean conflict, no WWII V 06 .Vietnam era and Korean conflict and WWII V 07 .February 1955 to July 1964 only V 08 .Korean conflict, no Vietnam era, no WWII V 09 .Korean conflict and WWII, no Vietnam era V 10 .WWII, no Korean conflict, no Vietnam era V 11 .Other service D SEPT80 1 75 Served September 1980 or later V 0 .(Did not serve this period/less than 16 years V .old) V 1 .Served this period 1 Page 112 ICPSR 6150 D MAY75880 1 76 Served May 1975 to August 1980 V 0 .(Did not serve this period/less than 16 years V .old) V 1 .Served this period D VIETNAM 1 77 Served Vietnam era (August 1964 - April 1975) V 0 .(Did not serve this period/less than 16 years V . old) V 1 .Served this period D FEB55 1 78 Served February 1955 - July 1964 V 0 .(Did not serve this period/less than 16 years V .old) V 1 .Served this period D KOREAN 1 79 Served Korean conflict (June 1950 - January 1955) V 0 .(Did not serve this period/less than 16 years V .old) V 1 .Served this period D WWII 1 80 Served World War II (September 1940 - July 1947) V 0 .(Did not serve this period/less than 16 years V .old) V 1 .Served this period D PFILLER2 1 81 D OTHRSERV 1 82 Served any other time V 0 .(Did not serve this period/less than 16 years V .old) V 1 .Served this period D YRSSERV 2 83 Years of active duty military service V 00 .N/A (less than 16 years/no active duty military V .service) V 01 .1 Year or less of service V 02..49 .2 to 49 years of service V 50 .50 or more years of service 1 ICPSR 6150 Page 113 D DISABL1 1 85 Work limitation status V 0 .N/A (less than 16 years, and selected persons in V .GQs - See appendix C) V 1 .Yes, limited in kind or amount of work V 2 .No, not limited D DISABL2 1 86 Work prevented status V 0 .N/A(less than 16 years, and selected persons in V .GQs - See appendix C) V 1 .Yes, prevented from working V 2 .No, not prevented from working D MOBILLIM 1 87 Mobility limitation V 0 .N/A (less than 15 years/institutionalized V .person, and selected persons in GQs - V .See appendix C) V 1 .Yes, has a mobility limitation V 2 .No, does not have a mobility limitation D PERSCARE 1 88 Personal care limitation V 0 .N/A (less than 15 years/institutionalized V .person, and selected persons in GQs - V .See appendix C) V 1 .Yes, has a personal care limitation V 2 .No, does not have a personal care limitation D FERTIL 2 89 Number of children ever born V 00 .N/A (less than 15 years/male) V 01 .No children V 02 .1 Child V 03 .2 Children V 04 .3 Children V 05 .4 Children V 06 .5 Children V 07 .6 Children V 08 .7 Children V 09 .8 Children V 10 .9 Children V 11 .10 Children V 12 .11 Children V 13 .12 or more children 1 Page 114 ICPSR 6150 D RLABOR 1 91 Employment status recode V 0 .N/A (less than 16 years old) V 1 .Civilian employed, at work V 2 .Civilian employed, with a job but not at work V 3 .Unemployed V 4 .Armed forces, at work V 5 .Armed forces, with a job but not at work V 6 .Not in labor force D WORKLWK 1 92 Worked last week V 0 .N/A (less than 16 years old/not at work/ V .unemployed/NILF/Q21A not reported) V 1 .Worked V 2 .Did not work D HOURS 2 93 Hours worked last week V 00 .N/A (less than 16 years old/not at V .work/unemployed/NILF) V 01..98 .1 to 98 hours worked last week V 99 .99 or more hours worked last week D POWSTATE 2 95 Place of work - state - (Appendix I) V 00 .N/A (not a worker--not in the labor force, V .including persons under 16 years; unemployed; V .employed, with a job not at work; Armed Forces, .With a job but not at work) V 01-56 .FIPS state code (U.S. States and D.C.) V 98 .Abroad V 99 .State not identified D POWPUMA 5 97 Place of work PUMA (State dependent) V 00000 .N/A (not a worker--not in the labor force, V .including persons under 16 years; V .unemployed; employed, with a job but not at V .work; Armed Forces, with a job but not at V .work) V 00100.. 99800 .PUMA of work * (Not coded to tract level) V 99900 .Abroad D MEANS 2 102 Means of transportation to work Revised, June 1993 1 ICPSR 6150 Page 115 V 00 .N/A (not a worker--not in the labor force, V .including persons under 16 years; unemployed; V .employed, with a job but not at work; Armed V .Forces, with a job but not at work) V 01 .Car, truck, or van V 02 .Bus or trolley bus V 03 .Streetcar or trolley car V 04 .Subway or elevated V 05 .Railroad V 06 .Ferryboat V 07 .Taxicab V 08 .Motorcycle V 09 .Bicycle V 10 .Walked V 11 .Worked at home V 12 .Other method D RIDERS 1 104 Vehicle occupancy V 0 .N/A (not a worker or worker whose means of V .transportation to work was not car, truck, V .or van) V 1 .Drove alone V 2 .2 People V 3 .3 People V 4 .4 People V 5 .5 People V 6 .6 People V 7 .7 to 9 people V 8 .10 or more people D DEPART 4 105 Time of departure for work - hour and minute V 0000 .N/A (not a worker or worker who worked at .home) V 0001.. 2400 .Time (hour and minute of departure for .work) (2400 midnight) D TRAVTIME 2 109 Travel time to work V 00 .N/A (not a worker or worker who worked at home) V 01..98 .1 to 98 minutes to get to work V 99 .99 Minutes or more to get to work D TMPABSNT 1 111 Temporary absence from work 1 Page 116 ICPSR 6150 V 0 .N/A (less than 16 years old/at work/did not .report Q25) V 1 .Yes, on layoff V 2 .Yes, on vacation, temporary illness, labor .dispute V 3 .No D LOOKING 1 112 Looking for work V 0 .N/A (less than 16 years old/at work/did not .report Q26A) V 1 .Yes V 2 .No D AVAIL 1 113 Available for work V 0 .N/A (less than 16 years/at work/not looking/ .Q26A = 0/did not report Q26B) V 1 .No, already has a job V 2 .No, temporarily ill V 3 .No, other reasons (in school,etc.) V 4 .Yes, could have taken a job D YEARWRK 1 114 Year last worked V 0 .N/A (less than 16 years old) V 1 .1990 V 2 .1989 V 3 .1988 V 4 .1985 to 1987 V 5 .1980 to 1984 V 6 .1979 or earlier V 7 .Never worked D INDUSTRY 3 115 Industry V 000 .N/A (less than 16 years old/unemployed who .never worked/NILF who last worked prior to .1985) V 010..992 .specific industry codes (see appendix I) D OCCUP 3 118 Occupation V 000 .N/A (less than 16 years old/unemployed who .never worked/NILF who last worked prior to .1985) V 003..909 .specific occupation codes (see appendix I) 1 ICPSR 6150 Page 117 D CLASS 1 121 Class of worker V 0 .N/A (less than 16 years old/unemployed who V .never worked/NILF who last worked prior to V .1985) V 1 .employee of a private for profit company or V .business or of an individual, for wages, V .salary, or commissions V 2 .Employee of a private not-for-profit, V .tax-exempt, or charitable organization V 3 .Local government employee (city, county, etc.) V 4 .State government employee V 5 .Federal government employee V 6 .Self-employed in own not incorporated V .business, professional practice, or farm V 7 .Self-employed in own incorporated V .business, professional practice or farm V 8 .Working without pay in family business or farm V 9 .Unemployed, last worked in 1984 or earlier D WORK89 1 122 Worked last year (1989) V 0 .N/A (less than 16 years old) V 1 .Worked last year V 2 .Did not work last year D WEEK89 2 123 Weeks worked last year (1989) V 00 .N/A (less than 16 years old/did not work in .1989) V 01..52 .1 to 52 weeks worked last year D HOUR89 2 125 Usual hours worked per week last year (1989) V 00 .N/A (less than 16 years old/did not work in .1989) V 01..98 .1 To 98 usual hours V 99 .99 Or more usual hours D REARNING 6 127 Total person's earnings V 000000 .N/A (no earnings) V -19996 .Loss of $19996 or more V -19995.. 283999 .Total person's earnings in dollars V 284000 .$284000 = Topcode V 284001+ .State medians included 1 Page 118 ICPSR 6150 D RPINCOME 6 133 Total person's income (signed) V 000000 .N/A (no income) V -29997 .Loss of $29997 or more V -29996.. 400999 .Total person's income in dollars V 401000 .Topcode of total person's income V 401001+ .State medians included D INCOME1 6 139 Wages or salary income in 1989 V 000000 .N/A (less than 16 years old/none) V 000001.. V 139999 .$1 - 139,999 V 140000 .Topcode V 140001+ .140001 or more = state median of topcoded V .values D INCOME2 6 145 Nonfarm self-employment income in 1989 (signed) V 000000 .N/A (less than 16 years/none) V -09999 .Loss of $9,999 or more V -00001.. V -09998 .Loss $1 to $9,998 V 000001 .Break even or $1 V 000002.. 089999 .$2 To $89999 V 090000 .Topcode V 090001+ .$90,001 or more = state median of topcoded .values D INCOME3 6 151 Farm self-employment income in 1989 (signed) V 000000 .N/A (less than 16 years/none) V -09999 .Loss of $9,999 or more V -00001 to -09998 .Loss $1 to $9,998 V 1 .Break even or $1 V 000002.. 053999 .$2 To $53999 V 054000 .Topcode V 054001+ .$54001 or more = state median of .topcoded values D INCOME4 6 157 Interest, dividends, and net rental income in 1989 (signed) 1 ICPSR 6150 Page 119 V 000000 .N/A (less than 15 years/none) V -09999 .Loss of $9,999 or more V -00001 to -09998 .Loss $1 to $9,998 V 1 .Break even or $1 V 000002.. 039999 .$2 To $39999 V 040000 .Topcode V 040001+ .$40001 or more = state median of .topcoded values D INCOME5 5 163 Social security income in 1989 V 00000 .N/A (less than 15 years/none) V 00001.. 16999 .$1 to $16999 V 17000 .Topcode V 17001+ .17001 or more = state median of topcoded .values D INCOME6 5 168 Public assistance income in 1989 V 00000 .N/A (less than 15 years/none) V 00001.. 9999 .$1 To $9999 V 10000 .Topcode V 10001+ .$10001 or more = state median D INCOME7 5 173 Retirement income in 1989 V 00000 .N/A (less than 15 years/none) V 00001.. 29999 .$1 to $29999 V 30000 .Topcode V 30001+ .$30001 or more = state median of topcoded .values D INCOME8 5 178 All other income in 1989 V 00000 .N/A (less than 15 years/none) V 00001.. 19999 .$1 to $19999 V 20000 .Topcode V 20001+ .$20,001 or more = state median of topcoded .values 1 Page 120 ICPSR 6150 D AAUGMENT 1 183 Augmented person (see text pp. C-5) V 0 .No V 1 .Yes D ARELAT1 1 184 Relationship allocation flag V 0 .No V 1 .Yes D ASEX 1 185 Sex allocation flag V 0 .No V 1 .Yes D ARACE 1 186 Detailed race allocation flag V 0 .No V 1 .Yes D AAGE 1 187 Age allocation flag V 0 .No V 1 .Yes D AMARITAL 1 188 Marital status allocation flag V 0 .No V 1 .Yes D AHISPAN 1 189 Detailed Hispanic origin allocation flag V 0 .No V 1 .Yes D ABIRTHPL 1 190 Place of birth V 0 .No V 1 .Yes D ACITIZEN 1 191 Citizenship allocation flag V 0 .No V 1 .Yes D AIMMIGR 1 192 Year of entry allocation flag V 0 .No V 1 .Yes 1 ICPSR 6150 Page 121 D ASCHOOL 1 193 School enrollment allocation flag V 0 .No V 1 .Yes D AYEARSCH 1 194 Highest education allocation flag V 0 .No V 1 .Yes D AANCSTR1 1 195 First ancestry allocation flag V 0 .No V 1 .Yes D AANCSTR2 1 196 Second ancestry allocation flag V 0 .No V 1 .Yes D AMOBLTY 1 197 Mobility status allocation flag V 0 .No V 1 .Yes D AMIGSTATE 1 198 Migration state allocation flag V 0 .No V 1 .Yes D ALANG1 1 199 Language other than English allocation flag V 0 .No V 1 .Yes D ALANG2 1 200 Language spoken at home allocation flag V 0 .No V 1 .Yes D AENGLISH 1 201 Ability to speak English allocation flag V 0 .No V 1 .Yes D AVETS1 1 202 Military service allocation flag V 0 .No V 1 .Yes 1 Page 122 ICPSR 6150 D ASERVPER 1 203 Military periods of service allocation flag V 0 .No V 1 .Yes D AYRSSERV 1 204 Years of military service allocation flag V 0 .No V 1 .Yes D ADISABL1 1 205 Work limitation status allocation flag V 0 .No V 1 .Yes D ADISABL2 1 206 Work prevention status allocation flag V 0 .No V 1 .Yes D AMOBLLIM 1 207 Mobility limitation status allocation flag V 0 .No V 1 .Yes D APERCARE 1 208 Personal care limitation status allocation flag V 0 .No V 1 .Yes D AFERTIL 1 209 Children ever born allocation flag V 0 .No V 1 .Yes D ALABOR 1 210 Employment status recode allocation flag V 0 .No V 1 .Yes D AHOURS 1 211 Hours worked last week allocation flag V 0 .No V 1 .Yes D APOWST 1 212 Place of work state allocation flag V 0 .No V 1 .Yes 1 ICPSR 6150 Page 123 D AMEANS 1 213 Means of transportation to work allocation flag V 0 .No V 1 .Yes D ARIDERS 1 214 Vehicle occupancy allocation flag V 0 .No V 1 .Yes D ADEPART 1 215 Time of departure to work allocation flag V 0 .No V 1 .Yes D ATRANTME 1 216 Travel time to work allocation flag V 0 .No V 1 .Yes D ALSTWRK 1 217 Year last worked allocation flag V 0 .No V 1 .Yes D AINDUSTR 1 218 Industry allocation flag V 0 .No V 1 .Yes D AOCCUP 1 219 Occupation allocation flag V 0 .No V 1 .Yes D ACLASS 1 220 Class of worker allocation flag V 0 .No V 1 .Yes D AWORK89 1 221 Worked last year allocation flag V 0 .No V 1 .Yes D AWKS89 1 222 Weeks worked in 1989 allocation flag V 0 .No V 1 .Yes 1 Page 124 ICPSR 6150 D AHOUR89 1 223 Usual hours worked per week in 1989 allocation flag V 0 .No V 1 .Yes D AINCOME1 1 224 Wages and salary income allocation flag V 0 .No V 1 .Yes D AINCOME2 1 225 Nonfarm self-employment income allocation flag V 0 .No V 1 .No (derived) V 2 .Yes D AINCOME3 1 226 Farm self-employment income allocation flag V 0 .No V 1 .No (derived) V 2 .Yes D AINCOME4 1 227 Interest, dividend, and net rental income allocation flag V 0 .No V 1 .No (derived) V 2 .Yes D AINCOME5 1 228 Social security income allocation flag V 0 .No V 1 .No (derived) V 2 .Yes D AINCOME6 1 229 Public assistance allocation flag V 0 .No V 1 .No (derived) V 2 .Yes D AINCOME7 1 230 Retirement income allocation flag V 0 .No V 1 .No (derived) V 2 .Yes 1 ICPSR 6150 Page 125 D AINCOME8 1 231 All other income allocation flag V 0 .No V 1 .No (derived) V 1 Page 126 ICPSR 6150 - 1 ICPSR 6150 Page 127 USER NOTES User Notes supply file purchasers with additional or corrected information which becomes available after the technical documentation or files are prepared. They are issued in a numbered series and automatically mailed to all users who purchase technical documentation from the Census Bureau. Other users may obtain them by subscribing to the User Note series. Contact Customer Services (301-763-4100) for subscription information. Each User Note has a cover sheet which should be filed following this page. Technical documentation replacement pages will follow the cover sheet. These pages need to be filed in their proper location and the original pages destroyed. Replacement pages can be readily identified, since they have the User Note date on the lower outside portion of each page. 1 Page 128 ICPSR 6150 - 1 ICPSR 6150 Page 129 UNITED STATES DEPARTMENT OF COMMERCE Bureau of the Census Washington, DC 20233-0001 June, 1993 To: Census of Population and Housing, 1990: Public Use Microdata Samples - United States Data Users From: Data Users Services Division Bureau of the Census Attached are User Notes 1, 2 and 3 for the 1990 Public Use Microdata Samples - U.S. data. Please file the user notes in the technical documentation as directed. It is probably a good idea to file the user note transmittal sheets in the user note section. Included in the user notes are revised pages that have been corrected for typographical errors. Corrections made on these pages are marked with an asterisk. These notes are sent automatically without charge to Census Bureau tape purchasers. They are available to others on a subscription basis at a cost of $40 annually. To subscribe, contact Customer Services, Data User Services Division, Bureau of the Census, Washington, DC 20233. User notes are available upon release from the State and Regional Programs electronic bulletin board. The bulletin board can be accessed on (301) 763-7554. 1 Page 130 ICPSR 6150 - 1 ICPSR 6150 Page 131 CENSUS OF POPULATION AND HOUSING, 1990. PUBLIC USE MICRODATA SAMPLES User NOTE 1 These are the first set of maps for Appendix G. We will release the PUMS maps on a flow basis until the series is completed. Please refer to the electronic equivalency files which accompanied your computer tape, for the components of each PUMA. Please place maps in Appendix G. ICPSR Note: A list of the components of the "99" file PUMAS has been appended to the end of the Geographic Equivalency File for the 1% PUMS. It is also provided in Appendix G. USER NOTES Revised, June 1993 1 Page 132 ICPSR 6150 - 1 ICPSR 6150 Page 133 CENSUS OF POPULATION AND HOUSING, 1990: PUBLIC USE MICRODATA SAMPLES USER NOTE 2 Please add the following pages (C-7 - C-12) to Appendix C. Pages C-7 - C-8 describe how to make estimates when combining the various PUMS files: (eg. 5%, 1% and 3% files). Pages C-9 through C-12 provide control counts and state medians for the files. ICPSR Note: Replacement pages have been inserted in the codebook. A footer indicating that pages have been revised can be found at the bottom of the new and revised pages. Relevant pages in the ICPSR codebook are as follows: 278-280, 281-283, 284-293 USER NOTES Revised, June 1993 1 Page 134 ICPSR 6150 - 1 ICPSR 6150 Page 135 CENSUS OF POPULATION AND HOUSING, 1990: PUBLIC USE MICRODATA SAMPLES USER NOTE 3 The following pages are replacement pages for various chapters in the technical documentation. These pages were corrected for typographical errors. Page numbers 5-2, 5-7, 5-15, 5-17, 5-18, 5-19, 5-20, 5-21, C-6, I-3, I-6, I-14, I-18, I-20, I-22 and I-28. Please add page I-i to Appendix I. ICIPSR Note: the above pages have been replaced in the data dictionary and codebook. In the data dictionary and code list, affected variables are denoted with an asterisk, as well as with a footer indicating that the page has been revised. Relevant pages in the ICPSR codebook are as follows: 73, 80, 99, 102, 106, 107, 110, 114, 353, 359-361, 366, 383, 394, 411-413 USER NOTES Revised, June 1993 1 Page 136 ICPSR 6150 - 1 ICPSR 6150 Page 137 APPENDIX A AREA CLASSIFICATIONS CONTENTS Page ALASKA NATIVE REGIONAL CORPORATION (ANRC) (See American Indian and Alaska Native Area) ALASKA NATIVE VILLAGE (ANV)(See American Indian and Alaska Native Area) ALASKA NATIVE VILLAGE STATISTICAL AREA (See American Indian and Alaska Native Area) AMERICAN INDIAN AND ALASKA NATIVE AREA........................... 141 AMERICAN INDIAN RESERVATION (See American Indian and Alaska Native Area, see County Subdivision) AMERICAN INDIAN RESERVATION AND TRUST LAND (See American Indian and Alaska Native Area) AMERICAN SAMOA (See Outlying Areas of the United States, see State) AREA MEASUREMENT................................................. 143 ASSESSMENT DISTRICT (See County Subdivision) BLOCK............................................................ 144 BLOCK GROUP (BG)................................................. 145 BLOCK NUMBERING AREA (BNA) (See Census Tract and Block Numbering Area) BOROUGH (See County Subdivision, see Place) BOROUGH AND CENSUS AREA (ALASKA) (See County) BOUNDARY CHANGES................................................. 146 CENSUS AREA (ALASKA) (See County) CENSUS BLOCK (See Block) CENSUS CODE (See Geographic Code) CENSUS COUNTY DIVISION (See County Subdivision) CENSUS DESIGNATED PLACE (CDP) (See Place) CENSUS DIVISION (See Census Region and Census Division) CENSUS GEOGRAPHIC CODE (See Geographic Code) CENSUS REGION AND CENSUS DIVISION................................ 146 CENSUS SUBAREA (ALASKA) (See County Subdivision) CENSUS TRACT AND BLOCK NUMBERING AREA............................ 148 CENTRAL CITY (See Metropolitan Area) CENTRAL PLACE (See Urbanized Area) CITY (See Place) CONGRESSIONAL DISTRICT........................................... 149 CONSOLIDATED CITY (See Place) CONSOLIDATED METROPOLITAN STATISTICAL AREA (CMSA) (See Metropolitan Area) 1 Page 138 ICPSR 6150 COUNTY........................................................... 150 COUNTY SUBDIVISION............................................... 150 CREWS OF VESSELS (See Area Measurement, see Block, see Census Tract and Block Numbering Area) DIVISION (See Census Region and Division, see County Subdivision) ELECTION DISTRICT (See County Subdivision, see Voting District) EXTENDED CITY (See Urban and Rural) FARM (See Urban and Rural) FEDERAL INFORMATION PROCESSING STANDARDS (FIPS) CODE (See Geographic Code) GEOGRAPHIC BLOCK GROUP (See Block Group) GEOGRAPHIC CODE.................................................. 152 GEOGRAPHIC PRESENTATION.......................................... 153 GORE (See County Subdivision) GRANT (See County Subdivision) GUAM (See Outlying Areas of the United States, see State) HIERARCHICAL PRESENTATION (See Geographic Presentation) HISTORIC AREAS OF OKLAHOMA (See American Indian and Alaska Native Area, Tribal Jurisdiction Statistical Area) HISTORICAL COUNTS................................................ 154 INCORPORATED PLACE (See Place) INDEPENDENT CITY (See County) INTERNAL POINT................................................... 154 INVENTORY PRESENTATION (See Geographic Presentation) LAND AREA (See Area Measurement) LATITUDE (See Internal Point) LONGITUDE (See Internal Point) MAGISTERIAL DISTRICT (See County Subdivision) METROPOLITAN AREA................................................ 155 METROPOLITAN STATISTICAL AREA (MSA) (See Metropolitan Area) MINOR CIVIL DIVISION (See County Subdivision) NORTHERN MARIANA ISLANDS (See Outlying Areas of the United States, see State) OUTLYING AREAS OF THE UNITED STATES.............................. 157 PALAU (See Outlying Areas of the United States, see State) PARISH (LOUISIANA) (See County) PARISH GOVERNING AUTHORITY DISTRICT (See County Subdivision) PLACE............................................................ 157 PLANTATION (See County Subdivision) POPULATION OR HOUSING UNIT DENSITY............................... 159 PRECINCT (See County Subdivision, see Voting District) PRIMARY METROPOLITAN STATISTICAL AREA (PMSA) (See Metropolitan Area) PUERTO RICO (See Outlying Areas of the United States, see State) PURCHASE (See County Subdivision) REGION (See Census Region and Census Division) 1 ICPSR 6150 Page 139 RURAL (See Urban and Rural) SELECTED STATES (See County Subdivision, see State) STATE............................................................ 159 SUPERVISORS' DISTRICT (See County Subdivision) TABULATION BLOCK GROUP (See Block Group) TIGER............................................................ 160 TOWN (See County Subdivision, see Place) TOWNSHIP (See County Subdivision) TRACT (See Census Tract and Block Numbering Area) TRIBAL DESIGNATED STATISTICAL AREA (TDSA) (See American Indian and Alaska Native Area) TRIBAL JURISDICTION STATISTICAL AREA (TJSA) (See American Indian and Alaska Native Area) TRUST LAND (See American Indian and Alaska Native Area) UNITED STATES.................................................... 160 UNORGANIZED TERRITORY (UNORG.) (See County Subdivision) URBAN AND RURAL.................................................. 161 URBANIZED AREA................................................... 162 VILLAGE (See Place) VIRGIN ISLANDS (See Outlying Areas of the United States, see State) VOTING DISTRICT (VTD)............................................ 164 WATER AREA (See Area Measurement) ZIP CODE * ...................................................... 164 These definitions are for all geographic entities and concepts that the Census Bureau will include in its standard 1990 census data products. Not all entities and concepts are shown in any one 1990 census data product. For a description of geographic areas included in each data product, see appendix F. 1 Page 140 ICPSR 6150 - 1 ICPSR 6150 Page 141 AMERICAN INDIAN AND ALASKA NATIVE AREA ALASKA NATIVE REGIONAL CORPORATION (ANRC) Alaska Native Regional Corporations (ANRC's) are corporate entities established under the Alaska Native Claims Settlement Act of 1972, Public Law 92-203, as amended by Public Law 94-204, to conduct both business and nonprofit affairs of Alaska Natives. Alaska is divided into 12 ANRC's that cover the entire State, except for the Annette Islands Reserve. The boundaries of the 12 ANRC's were established by the Department of the Interior, in cooperation with Alaska Natives. Each ANRC was designed to include, as far as practicable, Alaska Natives with a common heritage and common interests. The ANRC boundaries for the 1990 census were identified by the Bureau of Land Management. A 13th region was established for Alaska Natives who are not permanent residents and who chose not to enroll in one of the 12 ANRC's; no census products are prepared for the 13th region. ANRC's were first identified for the 1980 census. Each ANRC is assigned a two-digit census code ranging from 07 through 84. These census codes are assigned in alphabetical order of the ANRC's. ALASKA NATIVE VILLAGE (ANV) STATISTICAL AREA Alaska Native villages (ANV's) constitute tribes, bands, clans, groups, villages, communities, or associations in Alaska that are recognized pursuant to the Alaska Native Claims Settlement Act of 1972, Public Law 92-203. Because ANV's do not have legally designated boundaries, the Census Bureau has established Alaska Native village statistical areas (ANVSA's) for statistical purposes. For the 1990 census, the Census Bureau cooperated with officials of the nonprofit corporation within each participating Alaska Native Regional Corporation (ANRC), as well as other knowledgeable officials, to delineate boundaries that encompass the settled area associated with each ANV. ANVSA's are located within ANRC's and do not cross ANRC boundaries. ANVSA's for the 1990 census replace the ANV's that the Census Bureau recognized for the 1980 census. Each ANVSA is assigned a four-digit census code ranging from 6001 through 8989. Each ANVSA also is assigned a five-digit FIPS code. Both the census and FIPS codes are assigned in alphabetical order of ANVSA's. AMERICAN INDIAN RESERVATION AND TRUST LAND AMERICAN INDIAN RESERVATION--Federal American Indian reservations are areas with boundaries established by treaty, statute, and/or executive or court order, and recognized by the Federal Government as territory in which American Indian tribes have jurisdiction. State reservations are lands held in trust by State governments for the use 1 Page 142 ICPSR 6150 and benefit of a given tribe. The reservations and their boundaries were identified for the 1990 census by the Bureau of Indian Affairs (BIA), Department of Interior (for Federal reservations), and State governments (for State reservations). The names of American Indian reservations recognized by State governments, but not by the Federal Government, are followed by "(State)." Areas composed of reservation lands that are administered jointly and/or are claimed by two reservations, as identified by the BIA, are called "joint areas," and are treated as separate American Indian reservations for census purposes. Federal reservations may cross State boundaries, and Federal and State reservations may cross county, county subdivision, and place boundaries. For reservations that cross State boundaries, only the portion of the reservations in a given State are shown in the data products for that State; the entire reservations are shown in data products for the United States. Each American Indian reservation is assigned a four-digit census code ranging from 0001 through 4989. These census codes are assigned in alphabetical order of American Indian reservations nationwide, except that joint areas appear at the end of the code range. Each American Indian reservation also is assigned a five-digit FIPS code; because the FIPS codes are assigned in alphabetical sequence of American Indian reservations within each State, the FIPS code is different in each State for reservations in more than one State. TRUST LAND--Trust lands are property associated with a particular American Indian reservation or tribe, held in trust by the Federal Government. Trust lands may be held in trust either for a tribe (tribal trust land) or for an individual member of a tribe (individual trust land). Trust lands recognized for the 1990 census comprise all tribal trust lands and inhabited individual tribal lands located outside of a reservation boundary. As with other American Indian areas, trust lands may be located in more than one State. Only the trust lands in a given State are shown in the data products for that State; all trust lands associated with a reservation or tribe are shown in data products for the United States. The Census Bureau first reported data for tribal trust lands for the 1980 census. Trust lands are assigned a four-digit census code and a five-digit FIPS code, the same as that for the reservation with which they are associated Trust lands not associated with a reservation are presented by tribal name, interspersed alphabetically among the reservations. TRIBAL DESIGNATED STATISTICAL AREA (TDSA) Tribal designated statistical areas (TDSA's) are areas, delineated outside Oklahoma by federally-and State-recognized tribes without a land base or associated trust lands, to provide statistical areas for which the Census Bureau tabulates data. TDSA's represent areas generally containing the American Indian population over which federally-recognized tribes have jurisdiction and areas in which 1 ICPSR 6150 Page 143 State tribes provide benefits and services to their members. The names of TDSA's delineated by State-recognized tribes are followed by "(State)." The Census Bureau did not recognize TDSA's before the 1990 census. Each TDSA is assigned a four-digit census code ranging from 9001 through 9589. The census codes are assigned in alphabetical order of TDSA's nationwide. Each TDSA also is assigned a five-digit FIPS code in alphabetical order within State. TRIBAL JURISDICTION STATISTICAL AREA (TJSA) Tribal jurisdiction statistical areas (TJSA's) are areas, delineated by federally-recognized tribes in Oklahoma without a reservation, for which the Census Bureau tabulates data. TJSA's represent areas generally containing the American Indian population over which one or more tribal governments have jurisdiction; if tribal officials delineated adjacent TJSA's so that they include some duplicate territory, the overlap area is called a "joint use area," which is treated as a separate TJSA for census purposes. TJSA's replace the "Historic Areas of Oklahoma (excluding urbanized areas)" shown in 1980 census data products. The Historic Areas of Oklahoma comprised the territory located within reservations that had legally established boundaries from 1900 to 1907; these reservations were dissolved during the 2- to 3-year period preceding the statehood of Oklahoma in 1907. The Historic Areas of Oklahoma (excluding urbanized areas) were identified only for the 1980 census. Each TJSA is assigned a four-digit census code ranging from 5001 through 5989. The census codes are assigned in alphabetical order of TJSA's, except that joint areas appear at the end of the code range. Each TJSA also is assigned a five-digit FIPS code in alphabetical order within Oklahoma. AREA MEASUREMENT Area measurements provide the size, in square kilometers (also in square miles in printed reports), recorded for each geographic entity for which the Census Bureau tabulates data in general-purpose data products (except crews-of-vessels entities and ZIP Codes). (Square kilometers may be divided by 2.59 to convert an area measurement to square miles.) Area was calculated from the specific set of boundaries recorded for the entity in the Census Bureau's geographic data base (see "TIGER"). On machine-readable files, area measurements are shown to three decimal places; the decimal point is implied. In printed reports and listings, area measurements are shown to one decimal. The Census Bureau provides measurements for both land area and total water area for the 1990 census; the water figure includes inland, 1 Page 144 ICPSR 6150 coastal, Great Lakes, and territorial water. (For the 1980 census, the Census Bureau provided area measurements for land and inland water.) The Census Bureau will provide measurements for the component types of water for the affected entities in a separate file. "Inland water" consists of any lake, reservoir, pond, or similar body of water that is recorded in the Census Bureau's geographic data base. it also includes any river, creek, canal, stream, or similar feature that is recorded in that data base as a two-dimensional feature (rather than as a single line). The portions of the oceans and related large embayments (such as the Chesapeake Bay and Puget Sound), the Gulf of Mexico, and the Caribbean Sea that belong to the United States and its possessions are considered to be "coastal" and "territorial" waters; the Great Lakes are treated as a separate water entity. Rivers and bays that empty into these bodies of water are treated as "inland water" from the point beyond which they are narrower than one nautical mile across. Identification of land and inland, coastal, and territorial waters is for statistical purposes, and does not necessarily reflect legal definitions thereof. By definition, census blocks do not include water within their boundaries; therefore, the water area of a block is always zero. Land area measurements may disagree with the information displayed on census maps and in the TIGER file because, for area measurement purposes, features identified as "intermittent water" and "glacier" are reported as land area. For this reason, it may not be possible to derive the land area for an entity by summing the land area of its component census blocks. In addition, the water area measurement reported for some geographic entities includes water that is not included in any lower-level geographic entity. Therefore, because water is contained only in a higher-level geographic entity, summing the water measurements for all the component lower-level geographic entities will not yield the water area of that higher-level entity. This occurs, for example, where water is associated with a county but is not within the legal boundary at any minor civil division, or the water is associated with a State but is not within the legal boundary of any county. Crews-of -vessels entities (see "Census Tract and Block Numbering Area" and "Block") do not encompass territory and therefore have no area measurements. ZIP Codes do not have specific boundaries, and therefore, also do not have area measurements. The accuracy of any area measurement figure is limited by the inaccuracy inherent in (1) the location and shape of the various boundary features in the data base, and (2) rounding affecting the last digit in all operations that compute and/or sum the area measurements. BLOCK Census blocks are small areas bounded on all sides by visible features such as streets, roads, streams, and railroad tracks, and by invisible boundaries such as city, town, township, and county limits, 1 ICPSR 6150 Page 145 property lines, and short, imaginary extensions of streets and roads. Tabulation blocks, used in census data products, are in most cases the same as collection blocks, used in the census enumeration. In some cases, collection blocks have been "split" into two or more parts required for data tabulations. Tabulation blocks do not cross the boundaries of counties, county subdivisions, places, census tracts or block numbering areas. American Indian and Alaska Native areas, congressional districts, voting districts, urban or rural areas, or urbanized areas. The 1990 census is the first for which the entire United States and its possessions are block-numbered. Blocks are numbered uniquely within each census tract or BNA. A block is identified by a three-digit number, sometimes with a single alphabetical suffix. Block numbers with suffixes generally represent collection blocks that were "split" in order to identify separate geographic entities that divide the original block. For example, when a city limit runs through data collection block 101, the data for the portion inside the city is tabulated in block 101 A and the portion outside, in block 101B. A block number with the suffix "Z" represents a "crews-of-vessels" entity for which the Census Bureau tabulates data, but that does not represent a true geographic area; such a block is shown on census maps associated with an anchor symbol and a census tract or block numbering area with a .99 suffix. BLOCK GROUP (BG) GEOGRAPHIC BLOCK GROUP A geographic block group (BG) is a cluster of blocks having the same first digit of their three-digit identifying numbers within a census tract or block numbering area (BNA). For example, BG 3 within a census tract or BNA includes all blocks numbered between 301 and 397. In most cases, the numbering involves substantially fewer than 97 blocks. Geographic BG's never cross census tract or BNA boundaries, but may cross the boundaries of county subdivisions, places, American Indian and Alaska Native areas, urbanized areas, voting districts, and congressional districts. BG's generally contain between 250 and 550 housing units, with the ideal size being 400 housing units. TABULATION BLOCK GROUP In the data tabulations, a geographic BG may be split to present data for every unique combination of county subdivision, place, American Indian and Alaska Native area, urbanized area, voting district, urban/rural and congressional district shown in the data product; for example, if BG3 is partly in a city and partly outside the city, there will be separate tabulated records for each portion of BG3. BG's are used in tabulating decennial census data nationwide in the 1990 census, in all block-numbered areas in the 1980 census, and in Tape Address Register (TAR) areas in the 1970 census. For purposes 1 Page 146 ICPSR 6150 of data presentation, BG's are a substitute for the enumeration districts (ED's) used for reporting data in many parts of the United States for the 1970 and 1980 censuses, and in all areas for pre-1970 censuses. BOUNDARY CHANGES The boundaries of some counties, county subdivisions, American Indian and Alaska Native areas, and many incorporated places, changed between those reported for the 1980 census and January 1, 1990. Boundary changes to legal entities result from: 1. Annexations to or detachments from legally established governmental units. 2. Mergers or consolidations of two or more governmental units. 3. Establishment of new governmental units. 4. Disincorporations or disorganizations of existing governmental units. 5. Changes in treaties and Executive Orders. The historical counts shown for counties, county subdivisions, and places are not updated for such changes, and thus reflect the population and housing units in the area as delineated at each census. Information on boundary changes reported between the 1980 and 1990 censuses for counties, county subdivisions, and incorporated places is presented in the "User Notes" section of the technical documentation of Summary Tape Files 1 and 3, and in the 1990 CPH-2, Population and Housing Unit Counts printed reports. For information on boundary changes for such areas in the decade preceding other decennial censuses, see the Number of Inhabitants reports for each census. Boundary changes are not reported for some areas, such as census designated places and block groups. CENSUS REGION AND CENSUS DIVISION CENSUS DIVISION Census divisions are groupings of States that are subdivisions of the four census regions. There are nine divisions, which the Census Bureau adopted in 1910 for the presentation of data. The regions, divisions, and their constituent States are: NORTHEAST REGION New England Division: Maine, New Hampshire, Vermont, Massachusetts, Rhode Island, 1 ICPSR 6150 Page 147 Connecticut Middle Atlantic Division: New York, New Jersey, Pennsylvania MIDWEST REGION East North Central Division: Ohio, Indiana, Illinois, Michigan, Wisconsin West North Central Division: Minnesota, Iowa, Missouri, North Dakota, South Dakota, Nebraska, Kansas SOUTH REGION South Atlantic Division: Delaware, Maryland, District of Columbia, Virginia, West Virginia, North Carolina, South Carolina, Georgia, Florida East South Central Division: Kentucky, Tennessee, Alabama, Mississippi West South Central Division: Arkansas, Louisiana, Oklahoma, Texas WEST REGION Mountain Division: Montana, Idaho, Wyoming, Colorado, New Mexico, Arizona, Utah, Nevada Pacific Division: Washington, Oregon, California, Alaska, Hawaii CENSUS REGION Census regions are groupings of States that subdivide the United States for the presentation of data. There are four regions-Northeast, Midwest, South, and West. Each of the four census regions is divided into two or more census divisions. Prior to 1984, the Midwest region was named the North Central region. From 1910, when census regions were established, through the 1940's, there were 1 Page 148 ICPSR 6150 three regions-North, South, and West. CENSUS TRACT AND BLOCK NUMBERING AREA BLOCK NUMBERING AREA (BNA) Block numbering areas (BNA's) are small statistical subdivisions of a county for grouping and numbering blocks in nonmetropolitan counties where local census statistical areas committees have not established census tracts. State agencies and the Census Bureau delineated BNA's for the 1990 census, using guidelines similar to those for the delineation of census tracts. BNA's do not cross county boundaries. BNA's are identified by a four-digit basic number and may have a two-digit suffix; for example, 9901.07. The decimal point separating the four-digit basic BNA number from the two-digit suffix is shown in printed reports, in microfiche, and on census maps; in machine-readable files, the decimal point is implied. Many BNA's do not have a suffix; in such cases, the suffix field is left blank in all data products. BNA numbers range from 9501 through 9989.99, and are unique within a county (numbers in the range of 0001 through 9499.99 denote a census tract). The suffix .99 identifies a BNA that was populated entirely by persons aboard one or more civilian or military ships. A "crews-of-vessels" BNA appears on census maps only as an anchor symbol with its BNA number (and block numbers on maps showing block numbers); the BNA relates to the ships associated with the onshore BNA's having the same four-digit basic number. Suffixes in the range .80 through .98 usually identify BNA's that either were revised or were created during the 1990 census data collection activities. Some of these revisions produced BNA's that have extremely small land area and may have little or no population or housing. For data analysis, such a BNA can be summarized with an adjacent BNA. CENSUS TRACT Census tracts are small, relatively permanent statistical subdivisions of a county. Census tracts are delineated for all metropolitan areas (MA's) and other densely populated counties by local census statistical areas committees following Census Bureau guidelines (more than 3,000 census tracts have been established in 221 counties outside MA's). Six States (California, Connecticut, Delaware, Hawaii, New Jersey, and Rhode Island) and the District of Columbia are covered entirety by census tracts. Census tracts usually have between 2,500 and 8,000 persons and, when first delineated, are designed to be homogeneous with respect to population characteristics, economic status, and living conditions. Census tracts do not cross county boundaries. The spatial size of census tracts varies widely depending on the density of settlement. Census tract boundaries are delineated with the intention of being maintained over a long time so that statistical comparisons can be 1 ICPSR 6150 Page 149 made from census to census. However, physical changes in street patterns caused by highway construction, new development, etc., may require occasional revisions; census tracts occasionally are split due to large population growth, or combined as a result of substantial population decline. Census tracts are referred to as "tracts" in all 1990 data products. Census tracts are identified by a four-digit basic number and may have a two-digit suffix; for example, 6059.02. The decimal point separating the four-digit basic tract number from the two-digit suffix is shown in printed reports, in microfiche, and on census maps; in machine-readable files, the decimal point is implied. Many census tracts do not have a suffix; in such cases, the suffix field is left blank in all data products. Leading zeros in a census tract number (for example, 002502) are shown only on machine-readable files. Census tract numbers range from 0001 through 9499.99 and are unique within a county (numbers in the range of 9501 through 9989.99 denote a block numbering area). The suffix .99 identifies a census tract that was populated entirely by persons aboard one or more civilian or military ships. A "crews-of-vessels" census tract appears on census maps only as an anchor symbol with its census tract number (and block numbers on maps showing block numbers). These census tracts relate to the ships associated with the on-shore census tract having the same four-digit basic number. Suffixes in the range .80 through .98 usually identify census tracts that either were revised or were created during the 1990 census data collection activities. Some of these revisions may have resulted in census tracts that have extremely small land area and may have little or no population or housing. For data analysis, such a census tract can be summarized with an adjacent census tract. CONGRESSIONAL DISTRICT (CD) Congressional districts (CD's) are the 435 areas from which persons are elected to the U.S. House of Representatives. After the apportionment of congressional seats among the States, based on census population counts, each State is responsible for establishing CD's for the purpose of electing representatives. Each CD is to be as equal in population to all other CD's in the State as practicable, based on the decennial census counts. The CD's that were in effect on January 1, 1990 were those of the 101st Congress. Data on the 101st Congress appear in an early 1990 census data product (Summary Tape File 1A). The CD's of the 101st Congress are the same as those in effect for the 102nd Congress. CD's of the 103rd Congress, reflecting redistricting based on the 1990 census, are summarized in later 1990 data products (STF's 1D and 3D, and 1990 CPH-4, Population and Housing Characteristics for Congressional Districts of the 103rd Congress printed reports). 1 Page 150 ICPSR 6150 COUNTY The primary political divisions of most States are termed "counties." In Louisiana, these divisions are known as "parishes." In Alaska, which has no counties, the county equivalents are the organized "boroughs" and the "census areas" that are delineated for statistical purposes by the State of Alaska and the Census Bureau. In four States (Maryland, Missouri, Nevada, and Virginia), there are one or more cities that are independent of any county organization and thus constitute primary divisions of their States. These cities are known as "independent cities" and are treated as equivalent to counties for statistical purposes. That part of Yellowstone National Park in Montana is treated as a county equivalent. The District of Columbia has no primary divisions, and the entire area is considered equivalent to a county for statistical purposes. Each county and county equivalent is assigned a three-digit FIPS code that is unique within State. These codes are assigned in alphabetical order of county or county equivalent within State, except for the independent cities, which follow the listing of counties. COUNTY SUBDIVISION County subdivisions are the primary subdivisions of counties and their equivalents for the reporting of decennial census data. They include census county divisions, census subareas, minor civil divisions, and unorganized territories. Each county subdivision is assigned a three-digit census code in alphabetical order within county and a five-digit FIPS code in alphabetical order within State. CENSUS COUNTY DIVISION (CCD) Census county divisions (CCD's) are subdivisions of a county that were delineated by the Census Bureau, in cooperation with State officials and local census statistical areas committees, for statistical purposes. CCD's were established in 21 States where there are no legally established minor civil divisions (MCD's), where the MCD's do not have governmental or administrative purposes, where the boundaries of the MCD's change frequently, and/or where the MCD's are not generally known to the public. CCD's have no legal f unctions, and are not governmental units. The boundaries of CCD's usually are delineated to follow visible features, and in most cases coincide with census tract or block numbering area boundaries. The name of each CCD is based on a place, county, or well-known local name that identifies its location. CCD's have been established in the following 21 States: Alabama, Arizona, California, Colorado, Delaware, Florida, Georgia, Hawaii, Idaho, 1 ICPSR 6150 Page 151 Kentucky, Montana, Nevada, New Mexico, Oklahoma, Oregon, South Carolina, Tennessee, Texas, Utah, Washington, and Wyoming. For the 1980 census, the county subdivisions recognized for Nevada were MCD's. CENSUS SUBAREA (ALASKA) Census subareas are statistical subdivisions of boroughs and census areas (county equivalents) in Alaska. Census subareas were delineated cooperatively by the State of Alaska and the Census Bureau. The census subareas, identified first in 1980, replaced the various types of subdivisions used in the 1970 census. MINOR CIVIL DIVISION (MCD) Minor civil divisions (MCD's) are the primary political or administrative divisions of a county. MCD's represent many different kinds of legal entities with a wide variety of governmental and/or administrative functions. MCD's are variously designated as American Indian reservations, assessment districts, boroughs, election districts, gores, grants, magisterial districts, parish governing authority districts, plantations, precincts, purchases, supervisors' districts, towns, and townships. In some States, all or some incorporated places are not located in any MCD and thus serve as MCD's in their own right. In other States, incorporated places are subordinate to (part of the MCD's in which they are located, or the pattern is mixed-some incorporated places are independent of MCD's and others are subordinate to one or more MCD's. The Census Bureau recognizes MCD's in the following 28 States: Arkansas, Connecticut, Illinois, Indiana, Iowa, Kansas, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Nebraska, New Hampshire, New Jersey, New York, North Carolina, North Dakota, Ohio, Pennsylvania, Rhode Island, South Dakota, Vermont, Virginia, West Virginia, and Wisconsin. The District of Columbia has no primary divisions, and the entire area is considered equivalent to an MCD for statistical purposes. The MCD's in 12 selected States (Connecticut, Maine, Massachusetts, Michigan, Minnesota, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, Vermont, and Wisconsin) also serve as general-purpose local governments. The Census Bureau presents data for these MCD's in all data products in which it provides data for places. UNORGANIZED TERRITORY (UNORG.) In nine States (Arkansas, Iowa, Kansas, Louisiana, Maine, Minnesota, North Carolina, North Dakota, and South Dakota), some counties contain territory that is not included in an MCD recognized by the Census Bureau. Each separate area of unorganized territory in these States is recognized as one or more separate county subdivisions for census purposes. Each unorganized territory is given a descriptive 1 Page 152 ICPSR 6150 name, followed by the designation "unorg." GEOGRAPHIC CODE Geographic codes are shown primarily on machine-readable data products, such as computer tape and compact disc-read only memory (CD-ROM), but also appear on other products such as microfiche; they also are shown on some census maps. Codes are identified as "census codes" only if there is also a Federal Information Processing Standards (FIPS) code for the same geographic entity. A code that is not identified as either "census" or "FIPS" is usually a census code for which there is no FIPS equivalent, for for which the Census Bureau does not Lise the FIPS code. The exceptions, which use only the FIPS code in census products, are county, congressional district, and metropolitan area (that is, metropolitan statistical area, consolidated metropolitan statistical area, and primary metropolitan statistical area). CENSUS CODE Census codes are assigned for a variety of geographic entities, including American Indian and Alaska Native area, census division, census region, county subdivision, place, State, urbanized area, and voting district. The structure, format, and meaning of census codes appear in the 1990 census Geographic Identification Code Scheme, in the data dictionary portion of the technical documentation for summary tape files, CD-ROM's, and microfiche. FEDERAL INFORMATION PROCESSING STANDARDS (FIPS) CODE Federal Information Processing Standards (FIPS) codes are assigned for a variety of geographic entities, including American Indian and Alaska Native area, congressional district, county, county subdivision, metropolitan area, place, and State. The structure, format, and meaning of FIPS codes used in the census are shown in the 1990 census Geographic Identification Code Scheme; in the data dictionary portion of the technical documentation for summary tape files, CD-ROM's, and microfiche. The objective of the FIPS codes is to improve the use of data resources of the Federal Government and avoid unnecessary duplication and incompatibilities in the collection, processing, and dissemination of data. More information about FIPS and FIPS code documentation is available from the National Technical Information Service, Springfield, VA 22161. UNITED STATES POSTAL SERVICE (USPS) CODE United States Postal Service (USPS) codes for states are used in all 1990 data products. The codes are two-character alphabetic abbreviations. These codes are the same as the FIPS two-character 1 ICPSR 6150 Page 153 alphabetic abbreviations. GEOGRAPHIC PRESENTATION HIERARCHICAL PRESENTATION A hierarchical geographic presentation shows the geographic entities in a superior/subordinate structure in census products. This structure is derived from the legal, administrative, or a real relationships of the entities. The hierarchical structure is depicted in report tables by means of indentation, and is explained for machine-readable media in the discussion of file Structure in the geographic coverage portion of the abstract in the technical documentation. An example of hierarchical presentation is the "standard census geographic hierarchy": block, within block group, within census tract or block numbering area, within place, within county subdivision, within county, within State, within division, within region, within the United States. Graphically, this is shown as: United States Region Division State County County subdivision Place (or part) Census tract/block numbering area (or part) Block group (or part) Block INVENTORY PRESENTATION An inventory presentation of geographic entities is one in which all entities of the same type are shown in alphabetical or code sequence, without reference to their hierarchical relationships. Generally, an inventory presentation shows totals for entities that may be split in a hierarchical presentation, such as place, census tract/block numbering area, or block group. An example of a series of inventory presentations is: State, followed by all the counties in that State, followed by all the places in that State. Graphically, this is shown as: State County "A" County "B" County "C" Place "X" Place "Y" Place "Z" 1 Page 154 ICPSR 6150 HISTORICAL COUNTS Historical counts for total population and total housing units are shown in the 1990 CPH-2, Population and Housing Unit Counts report series. As in past censuses, the general rule for presenting historical data for States, counties, county subdivisions, and places is to show historical counts only for single, continually existing entities. Stated another way, if an entity existed for both the current and preceding censuses, the tables show counts for the preceding censuses. Included in this category are entities of the same type (county, county subdivision, place) even if they had changed their names. Also included are entities that merged, but only if the new entity retained the name of one of the merged entities. The historical counts shown are for each entity as it was bounded at each census. In cases where an entity was formed since a preceding census, such as a newly incorporated place or a newly organized township, the symbol three dots "..." is shown for earlier censuses. The three-dot symbol also is shown for those parts of a place that have extended into an additional county or county subdivision through annexation or other revision of boundaries since the preceding census. In a few cases, changes in the boundaries of county subdivisions caused a place to be split into two or more parts, or to be split differently than in the preceding census. If historical counts for the parts of the place as currently split did not appear in a preceding census, "(NA)" is shown for the place in each county subdivision; however, the historical population and housing unit counts of the place appear in tables that show the entire place. For counties, county subdivisions, and places formed since January 1, 1980, 1980 census population and housing unit counts in the 1990 territory are reported in the geographic change notes included in the "User Notes" text section of 1990 CPH-2, Population and Housing Unit Counts, and in the technical documentation of Summary Tape Files 1 and 3. In some cases, population and housing unit counts for individual areas were revised since publication of the 1980 reports (indicated by the prefix "F"). In a number of tables of 1990 CPH-2, Population and Housing Unit Counts, 1980 counts are shown for aggregations of individual areas, such as the number, population, and housing unit counts of places in size groups, or urban and rural distributions. Revisions of population and housing unit counts for individual areas were not applied to the various aggregations. Therefore, it may not be possible to determine the individual areas in a given aggregation using the historical counts; conversely, the sum of the counts shown for individual areas may not agree with the aggregation. INTERNAL POINT 1 ICPSR 6150 Page 155 An internal point is a set of geographic coordinates (latitude and longitude) that is located within a specified geographic entity. A single point is identified for each entity; for many entities, this point represents the approximate geographic center of that entity. If the shape of the entity caused this point to be located outside the boundaries of the entity, it is relocated from the center so that it is within the entity. If the internal point for a block falls in a water area, it is relocated to a land area within the block. On machine-readable products, internal points are shown to six decimal places; the decimal point is implied. METROPOLITAN AREA The general concept of a metropolitan area (MA) is one of a large population nucleus, together with adjacent communities that have a high degree of economic and social integration with that nucleus. Some MA's are defined around two or more nuclei. The MA classification is a statistical standard, developed for use by Federal agencies in the production, analysis, and publication of data on MA's. The MA's are designated and defined by the Federal Office of Management and Budget, following a set of official published standards. These standards were developed by the interagency Federal Executive Committee on Metropolitan Areas, with the aim of producing definitions that are as consistent as possible for all MA's nationwide. Each MA must contain either a place with a minimum population of 50,000 or a Census Bureau-defined urbanized area and a total MA population of at least 100,000 (75,000 in New England). An MA comprises one or more central counties. An MA also may include one or more outlying counties that have close economic and social relationships with the central county. An outlying county must have a specified level of commuting to the central counties and also must meet certain standards regarding metropolitan character, such as population density, urban population, and population growth. In New England MA's are composed of cities and towns rather than whole counties. The territory, population, and housing units in MA's are referred to as "metropolitan." The metropolitan category is subdivided into "inside central city" and "outside central city." The territory, population, and housing units located outside MA's are referred to as "nonmetropolitan." The metropolitan and nonmetropolitan classification cuts across the other hierarchies; for example, there is generally both urban and rural territory within both metropolitan and nonmetropolitan areas. To meet the needs of various users, the standards provide for a flexible structure of metropolitan definitions that classify an MA either as a metropolitan statistical area (MSA), or as a consolidated 1 Page 156 ICPSR 6150 metropolitan statistical area (CMSA) that is divided into primary metropolitan statistical areas (PMSA's). Documentation of the MA standards and how they are applied is available from the Secretary, Federal Executive Committee on Metropolitan Areas, Population Division, U.S. Bureau of the Census, Washington, DC 20233. CENTRAL CITY In each MSA and CMSA, the largest place and, in some cases, additional places are designated as "central cities" under the official standards. A few PMSA's do not have central cities, The largest central city and, in some cases, up to two additional central cities are included in the title of the MA; there also are central cities that are not included in an MA title. An MA central city does not include any part of that city that extends outside the MA boundary. CONSOLIDATED AND PRIMARY METROPOLITAN STATISTICAL AREA (CMSA AND PMSA) If an area that qualifies as an MA has more than one million persons, primary metropolitan statistical areas (PMSA's) may be defined within it. PMSA's consist of a large urbanized county or cluster of counties that demonstrates very strong internal economic and social links, in addition to close ties to other portions of the larger area. When PMSA's are established, the larger area of which they are component parts is designated a consolidated metropolitan statistical area (CMSA). METROPOLITAN STATISTICAL AREA (MSA) Metropolitan statistical areas (MSA's) are relatively freestanding MA's and are not closely associated with other MA's. These areas typically are surrounded by nonmetropolitan counties. METROPOLITAN AREA TITLE AND CODE The title of an MSA contains the name of its largest central city, and up to two additional city names, provided that the additional places meet specified levels of population, employment, and commuting. Generally, a city with a population of 250,000 or more is in the title, regardless of other criteria. The title of a PMSA may contain up to three place names, as determined above, or up to three county names, sequenced in order of population. A CMSA title also may include up to three names, the first of which generally is the most populous central city in the area. The second name may be the first city or county name in the most populous remaining PMSA; the third name may be the first city or county name in the next most populous PMSA. A regional designation may be substituted for the second and/or third names in a CMSA title 1 ICPSR 6150 Page 157 if such a designation is supported by local opinion and is deemed to be unambiguous and suitable by the Office of Management and Budget. The titles for all MA's also contain the name of each State in which the area is located. Each metropolitan area is assigned a four-digit FIPS code, in alphabetical order nationwide. If the fourth digit of the code is a "2," it identifies a CMSA. Additionally, there is a separate set of two-digit codes for CMSA's, also assigned alphabetically. OUTLYING AREAS OF THE UNITED STATES The Census Bureau treats the outlying areas as the statistical equivalents of States for the 1990 census. The outlying areas are American Samoa, Guam, the Commonwealth of Northern Mariana Islands (Northern Mariana Islands), Republic of Palau (Palau), Puerto Rico, and the Virgin Islands of the United States. (Virgin Islands) Geographic definitions specific to each outlying area are shown in appendix A of the text in the data products for each area. PLACE Places, for the reporting of decennial census data, include census designated places and incorporated places. Each place is assigned a four-digit census code that is unique within State. Each place is also assigned a five-digit FIPS code that is unique within State. Both the census and FIPS codes are assigned based on alphabetical order within State. Consolidated cities (see below) are assigned a one-character alphabetical census code that is unique nationwide and a five-digit FIPS code that is unique within State. CENSUS DESIGNATED PLACE (CDP) Census designated places (CDP's) are delineated for the decennial census as the statistical counterparts of incorporated places. CDP's comprise densely settled concentrations of population that are identifiable by name, but are not legally incorporated places. Their boundaries, which usually coincide with visible features or the boundary of an adjacent incorporated place, have no legal status, nor do these places have officials elected to serve traditional municipal functions. CDP boundaries may change with changes in the settlement pattern; a CDP with the same name as in previous censuses does not necessarily have the same boundaries. Beginning with the 1950 census, the Census Bureau, in cooperation with State agencies and local census statistical areas committees, has identified and delineated boundaries for CDP's. In the 1990 census, the name of each such place is followed by "CDP." In the 1980 census, "(CDP)" was used; in 1970, 1960, and 1950 censuses, these places were identified by "(U)," meaning "unincorporated place." 1 Page 158 ICPSR 6150 To qualify as a CDP for the 1990 census, an unincorporated community must have met the following criteria: 1. In all States except Alaska and Hawaii, the Census Bureau uses three population size criteria to designate a CDP. These criteria are: a. 1,000 or more persons if outside the boundaries of an urbanized area (UA) delineated for the 1980 census or a subsequent special census. b. 2,500 or more persons if inside the boundaries of a UA delineated for the 1980 census or a subsequent special census. c. 250 or more persons if outside the boundaries of a UA delineated for the 1980 census or a subsequent special census, and within the official boundaries of an American Indian reservation recognized for the 1990 census. 2. In Alaska, 25 or more persons if outside a UA, and 2,500 or more persons if inside a UA delineated for the 1980 census or a subsequent special census. 3. In Hawaii, 300 or more persons, regardless of whether the community is inside or outside a UA. For the 1990 census, CDP's qualified on the basis of the population counts prepared for the 1990 Postcensus Local Review Program. Because these counts were subject to change, a few CDP's may have final population counts lower than the minimums shown above. Hawaii is the only State with no incorporated places recognized by the Bureau of the Census. All places shown for Hawaii in the data products are CDP's. By agreement with the State of Hawaii, the Census Bureau does not show data separately for the city of Honolulu. which is coextensive with Honolulu County. CONSOLIDATED CITY A consolidated government is a unit of local government for which the functions of an incorporated place and its county or minor civil division (MCD) have merged. The legal aspects of this action may result in both the primary incorporated place and the county or MCD continuing to exist as legal entities, even though the county or MCD performs few or no governmental functions and has few or no elected officials. Where this occurs, and where one or more other incorporated places in the county or MCD continue to function as separate governments, even though they have been included in the consolidated government, the primary incorporated place is referred to as a "consolidated city." 1 ICPSR 6150 Page 159 The data presentation for consolidated cities varies depending upon the geographic presentation. In hierarchical presentations, consolidated cities are not shown. These presentations include the semi-independent places and the "consolidated city (remainder)." Where the consolidated city is coextensive with a county or county subdivision, the data shown for those areas in hierarchical presentations are equivalent to those for the consolidated government. For inventory geographic presentations, the consolidated city appears at the end of the listing of places. The data for the consolidated city include places that are part of the consolidated city. The "consolidated city (remainder)" is the portion of the consolidated government minus the semi-independent places, and is shown in alphabetical sequence with other places. In summary presentations by size of place, the consolidated city is not included. The places semi-independent of consolidated cities are categorized by their size, as is the "consolidated city (remainder)." Each consolidated city is assigned a one-character alphabetic census code. Each consolidated city also is assigned a five-digit FIPS code that is unique within State. The semi-independent places and the "consolidated city (remainder)" are assigned a f our-digit census code and a five-digit FIPS place code that are unique within State. Both the census and FIPS codes are assigned based on alphabetical order within State. INCORPORATED PLACE Incorporated places recognized in 1990 census data products are those reported to the Census Bureau as legally in existence on January 1, 1990 under the laws of their respective States as cities, boroughs, towns, and villages, with the following exceptions: the towns in the New England States, New York, and Wisconsin, and the boroughs in New York are recognized as minor civil divisions for census purposes; the boroughs in Alaska are county equivalents. POPULATION OR HOUSING UNIT DENSITY Population or housing unit density is computed by dividing the total population or housing units of a geographic unit (for example, United States, State, county, place) by its land area measured in square kilometers or square miles. Density is expressed as both "persons (or housing units) per square kilometer" and "persons (or housing units) per square mile" of land area in 1990 census printed reports. STATE States are the primary governmental divisions of the United States. The District of Columbia is treated as a statistical equivalent of a 1 Page 160 ICPSR 6150 State for census purposes. The four census regions, nine census divisions, and their component States are shown under "CENSUS REGION AND CENSUS DIVISION" in this appendix. The Census Bureau treats the outlying areas as State equivalents for the 1990 census. The outlying areas are American Samoa, Guam, the Northern Mariana Islands, Palau, Puerto Rico, and the Virgin Islands of the United States. Geographic definitions specific to each outlying area are shown in appendix A in the data products for each area. Each State and equivalent is assigned a two-digit numeric Federal Information Processing Standards (FIPS) code in alphabetical order by State name, followed by the outlying area names. Each State and equivalent area also is assigned a two-digit census code. This code is assigned on the basis of the geographic sequence of each State within each census division; the first digit of the code is the code for the respective division. Puerto Rico, the Virgin Islands, and the outlying areas of the Pacific are assigned "O" as the division code. Each State and equivalent area also is assigned the two-letter FIPS/ United States Postal Service (USPS) code. In 12 selected States (Connecticut, Maine, Massachusetts, Michigan, Minnesota, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, Vermont, and Wisconsin), the minor civil divisions also serve as general-purpose local governments. The Census Bureau presents data for these minor civil divisions in all data products in which it provides data for places. TIGER TIGER is an acronym for the new digital (computer-readable) geographic data base that automates the mapping and related geographic activities required to support the Census Bureau's census and survey programs. The Census Bureau developed the Topologically Integrated Geographic Encoding and Referencing (TIGER) System to automate the geographic support processes needed to meet the major geographic needs of the 1990 census: producing the cartographic products to support data collection and map publication, providing the geographic structure for tabulation and publication of the collected data, assigning residential and employer addresses to their geographic location and relating those locations to the Census Bureau's geographic units, and so forth. The content of the TIGER data base is made available to the public through a variety of "TIGER Extract" files that may be obtained from the Data User Services Division, U.S. Bureau of the Census, Washington, DC 20233. UNITED STATES The United States comprises the 50 States and the District of Columbia. In addition, the Census Bureau treats the outlying areas 1 ICPSR 6150 Page 161 as statistical equivalents of States for the 1990 census. The outlying areas include American Samoa, Guam, the Northern Mariana Islands, Palau, Puerto Rico, and the Virgin Islands of the United States. URBAN AND RURAL The Census Bureau defines "urban" for the 1990 census as comprising all territory, population, and housing units in urbanized areas and in places of 2,500 or more persons outside urbanized areas, More specifically, "urban" consists of territory, persons, and housing units in: 1. Places of 2,500 or more persons incorporated as cities, villages, boroughs (except in Alaska and New York), and towns (except in the six (New England States, New York, and Wisconsin), but excluding the rural portions of "extended cities." 2. Census designated places of 2,500 or more persons. 3. Other territory, incorporated or unincorporated, included in urbanized areas. Territory, population, and housing units not classified as urban constitute "rural." In the 100-percent data products, "rural" is divided into "places of less than 2,500" and "not in places." The "not in places" category comprises "rural" outside incorporated and census designated places and the rural portions of extended cities. In many data products, the term "other rural" is used; "other rural" is a residual category specific to the classification of the rural in each data product. In the sample data products, rural population and housing units are subdivided into "rural farm" and "rural nonfarm." "Rural farm" comprises all rural households and housing units on farms (places from which $1,000 or more of agricultural products were sold in 1989); "rural nonfarm" comprises the remaining rural. The urban and rural classification cuts across the other hierarchies; for example, there is generally both urban and rural territory within both metropolitan and nonmetropolitan areas. In censuses prior to 1950, "urban" comprised all territory, persons, and housing units in incorporated places of 2,500 or more persons, and in areas (usually minor civil divisions) classified as urban under special rules relating to population size and density. The definition of urban that restricted itself to incorporated places having 2,500 or more persons excluded many large, densely settled areas merely because they were not incorporated. Prior to the 1950 census, the Census Bureau attempted to avoid some of the more obvious 1 Page 162 ICPSR 6150 omissions by classifying selected areas as "urban under special rules." Even with these rules, however, many large, closely built-up areas were excluded from the urban category. To improve its measure of urban territory, population, and housing units, the Census Bureau adopted the concept of the urbanized area and delineated boundaries for unincorporated places (now, census designated places) for the 1950 census. Urban was defined as territory, persons, and housing units in urbanized areas and, outside urbanized areas, in all places, incorporated or unincorporated, that had 2,500 or more persons. With the following three exceptions, the 1950 census definition of urban has continued substantially unchanged. First, in the 1960 census (but not in the 1970, 1980, or 1990 censuses), certain towns in the New England States, townships in New Jersey and Pennsylvania, and Arlington County, Virginia, were designated as urban. However, most of these "special rule" areas would have been classified as urban anyway because they were included in an urbanized area or in an unincorporated place of 2,500 or more persons. Second, "extended cities" were identified for the 1970, 1980, and 1990 censuses. Extended cities primarily affect the figures for urban and rural territory (area), but have very little effect on the urban and rural population and housing units at the national and State levels although for some individual counties and urbanized areas, the effects have been more evident. Third, changes since the 1970 census in the criteria for defining urbanized areas have permitted these areas to be defined around smaller centers. Documentation of the urbanized area and extended city criteria is available from the Chief, Geography Division, U.S. Bureau of the Census, Washington, DC 20233. EXTENDED CITY Since the 1960 census, there has been a trend in some States toward the extension of city boundaries to include territory that is essentially rural in character. The classification of all the population and living quarters of such places as urban would include in the urban designation territory, persons, and housing units whose environment is primarily rural. For the 1970,1980, and 1990 censuses, the Census Bureau identified as rural such territory and its population and housing units for each extended city whose closely settled area was located in an urbanized area. For the 1990 census, this classification also has been applied to certain places outside urbanized areas. In summary presentations by size of place, the urban portion of an extended city is classified by the population of the entire place; the rural portion is included in "other rural." URBANIZED AREA (UA) 1 ICPSR 6150 Page 163 The Census Bureau delineates urbanized areas (UA's) to provide a better separation of urban and rural territory, population, and housing in the vicinity of large places. A UA comprises one or more places ("central place") and the adjacent densely settled surrounding territory ("urban fringe") that together have a minimum of 50,000 persons. The urban fringe generally consists of contiguous territory having a density of least 1,000 persons per square mile. The urban fringe also includes outlying territory of such density if it was connected to the core of the contiguous area by road and is within 1 1/2 road miles of that core, or within 5 road miles of the core but separated by water or other undevelopable territory. Other territory with a population density of fewer than 1,000 people per square mile is included in the urban fringe if it eliminates an enclave or closes an indentation in the boundary of the urbanized area. The population density is determined by (1) outside of a place, one or more contiguous census blocks with a population density of at least 1,000 persons per square mile or (2) inclusion of a place containing census blocks that have at least 50 percent of the population of the place and a density of at least 1,000 persons per square mile. The complete criteria are available from the Chief, Geography Division, U.S. Bureau of the Census, Washington, DC 20233. URBANIZED AREA CENTRAL PLACE One or more central places function as the dominant centers of each UA. The identification of a UA central place permits the comparison of this dominant center with the remaining territory in the UA. There is no limit on the number of central places, and not all central places are necessarily included in the UA title. UA central places include: 1. Each place entirely (or partially, if the place is an extended city) within the UA that is a central city of a metropolitan area (MA). 2. If the UA does not contain an MA central city or is located outside of an MA, the central place(s) is determined by population size. URBANIZED AREA TITLE AND CODE The title of a UA identifies those places that are most important within the UA; it links the UA to the encompassing MA, where appropriate. If a single MA includes most of the UA, the title and code of the UA generally are the same as the title and code of the MA. If the UA is not mostly included in a single MA, if it does not include any place that is a central city of the encompassing MA, or if it is not located in an MA, the Census Bureau uses the population size of the included places, with a preference for incorporated places, to determine the UA title. The name of each State in which the UA is located also is in each UA title. 1 Page 164 ICPSR 6150 The numeric code used to identity each UA is the same as the code for the mostly encompassing MA (including CMSA and PMSA). If MA title cities represent multiple UA's, or the UA title city does not correspond to the first name of an MA title, the Census Bureau assigns a code based on the alphabetical sequence of the UA title in relationship to the other UA and MA titles. VOTING DISTRICT (VTD) A voting district (VTD) is any of a variety of types of areas (for example, election districts, precincts, wards, legislative districts) established by State and local governments for purposes of elections. For census purposes, each State participating in Phase 2 of the 1990 Census Redistricting Data Program outlined the boundaries of VTD's around groups of whole census blocks on census maps. The entities identified as VTD's are not necessarily those legally or currently established Also, to meet the "whole block" criterion, a State may have had to adjust VTD boundaries to nearby block boundaries. Therefore, the VTD's shown on the 1990 census tapes, listings, and maps may not represent the actual VTD's in effect at the time of the census. In the 1980 census, VTD's were referred to as "election precincts." Each VTD is assigned a four-character alphanumeric code that is unique within each county. The code "ZZZZ" is assigned to nonparticipating areas; the Census Bureau reports data for areas coded "ZZZZ." ZIP CODE ZIP Codes are administrative units established by the United States Postal Service (USPS) for the distribution of mail. ZIP Codes serve addresses for the most efficient delivery of mail, and therefore generally do not respect political or census statistical area boundaries. ZIP Codes usually do not have clearly identifiable boundaries, often serve a continually changing area are changed periodically to meet postal requirements, and do not cover all the land area of the United States. ZIP Codes are identified by five-digit codes assigned by the USPS. The first three digits identify a major city or sectional distribution center, and the last two digits generally signify a specific post office's delivery area or point. For the 1990 census, ZIP Code data are tabulated for the five-digit codes in STF 3B. 1 ICPSR 6150 Page 165 APPENDIX B. Definitions of Subject Characteristics CONTENTS POPULATION CHARACTERISTICS--------------------------------------- 169 Ability to Speak English (See Language Spoken at Home and Ability to speak English) Actual Hours Worked Last Week (See Employment Status) Age ------------------------------------------------------------- 169 American Indian Tribe (See Race) Ancestry -------------------------------------------------------- 170 Carpooling (See Journey to Work) Children Ever Born (See Family) Citizenship ----------------------------------------------------- 173 Civilian Labor Force (See Employment Status) Class of Worker (See Industry, Occupation, and Class of Worker) Disability (See Mobility Limitation Status, see Self-Care Limitation Status, see Work Disability Status) Earnings in 1989 (See Income in 1989) Educational Attainment ------------------------------------------ 174 Employment Status ----------------------------------------------- 176 Families (See Household Type and Relationship) Family Composition (See Household Type and Relationship) Family Income in 1989 (See Income in 1989) Family Size (See Household Type and Relationship) Family Type (See Household Type and Relationship) Farm Population (See Farm Residence under Housing Characteristics) Fertility ------------------------------------------------------- 179 Foreign-Born Persons (See Place of Birth) Foster Children (See Household Type and Relationship) Group Quarters -------------------------------------------------- 180 Hispanic Origin ------------------------------------------------- 191 Household (See Household Type and Relationship) Householder (See Household Type and Relationship) Income Deficit (See Income in 1989) Income in 1989 -------------------------------------------------- 198 Income Type in 1989 (See Income in 1989) Industry, Occupation, and Class of Worker ----------------------- 205 Institutionalized Persons (See Group Quarters) Journey to Work ------------------------------------------------- 210 Labor Force Status (See Employment Status) Language Spoken at Home and Ability to Speak English ------------ 215 Linguistic Isolation (See Language Spoken at Home and Ability to Speak English ) 1 Page 166 ICPSR 6150 Marital Status -------------------------------------------------- 221 Married Couples (See Marital Status) Means of Transportation (See Journey to Work) Migration (See Residence in 1985) Mobility Limitation Status -------------------------------------- 223 Nativity (See Place of Birth) Nonistitutionalized Group Quarters (See Group Quarters) Occupation (See Industry, Occupation, and Class of Worker) Own children (See Household Type and Relationship) Per Capita Income (See Income in 1989) Period of Military Service (See Veteran Status) Persons in Family (See Household Type and Relationship) Persons in Household (See Household Type and Relationship) Place of Birth -------------------------------------------------- 223 Place of Work (See Journey to Work) Poverty Status in 1989 ------------------------------------------ 224 Presence of Children (See Household Type and Relationship) Private Vehicle Occupancy (See Journey to Work) Race ------------------------------------------------------------ 229 Reference Week -------------------------------------------------- 236 Related Children (See Household Type and Relationship) Residence in 1985 ----------------------------------------------- 236 School Enrollment and Labor Force Status ------------------------ 238 School Enrollment and Type of School ---------------------------- 238 Self-Care Limitation Status ------------------------------------- 241 Sex ------------------------------------------------------------- 242 Spanish Origin (See Hispanic Origin) Stepfamily (See Household Type and Relationship) Subfamily (See Household Type and Relationship) Time Leaving Home to Go to Work (See Journey to Work) Travel Time to Work (See Journey to Work) Type of School (See School Enrollment and Type of School) Usual Hours Worked in 1989 (See Work Status in 1989) Veteran Status -------------------------------------------------- 242 Weeks Worked in 1989 (See Work Status in 1989) Work Disability Status ------------------------------------------ 243 Work Status in 1989 --------------------------------------------- 244 Worker (See Employment Status, see Industry, Occupation, and Class of Worker, see Journey to Work, see Worker Status in 1989) Workers in Family in 1989 (See work Status in 1989) Year of Entry --------------------------------------------------- 245 Years of Military Service (See Veteran Status) HOUSING CHARACTERISTICS ----------------------------------------- 246 Acreage --------------------------------------------------------- 248 Age of Structure (See Year Structure Built) Agricultural Sales ---------------------------------------------- 249 Bedrooms -------------------------------------------------------- 249 1 ICPSR 6150 Page 167 Boarded-Up Status ----------------------------------------------- 249 Business on Property -------------------------------------------- 250 Condominium Fee ------------------------------------------------- 250 Condominium Status ---------------------------------------------- 251 Congregate Housing (See Meal Included in Rent) Contract Rent --------------------------------------------------- 251 Crop Sales (See Agricultural Sales) Duration of Vacancy --------------------------------------------- 253 Farm Residence -------------------------------------------------- 253 Gross Rent ------------------------------------------------------ 254 Gross Rent as a Percentage of Household Income in 1989 ---------- 254 Homeowner Vacancy Rate (See Vacancy Status) House Heating Fuel ---------------------------------------------- 254 Housing Units (See Living Quarters) Insurance for Fire, Hazard, and Flood --------------------------- 255 Kitchen Facilities ---------------------------------------------- 256 Living Quarters ------------------------------------------------- 246 Meals included in Rent ------------------------------------------ 256 Mobile Home Costs ----------------------------------------------- 256 Months Vacant (See Duration of Vacancy) Mortgage Payment ------------------------------------------------ 257 Mortgage Status ------------------------------------------------- 257 Occupied Housing Units (See Living Quarters) Owner-Occupied Housing Units (See Tenure) Persons in Unit ------------------------------------------------- 258 Persons per Room ------------------------------------------------ 259 Plumbing Facilities --------------------------------------------- 259 Poverty Status of Households in 1989 ---------------------------- 259 Real Estate Taxes ----------------------------------------------- 260 Rental Vacancy Rate (See Vacancy Status) Renter-Occupied Housing Units (See Tenure) Rooms ----------------------------------------------------------- 260 Second or Junior Mortgage Payment ------------------------------- 261 Selected Monthly Owner Costs ------------------------------------ 262 Selected Monthly Owner Costs as a Percentage of Household Income in 1989 ------------------------------------------------------- 263 Sewage Disposal ------------------------------------------------- 263 Source of Water ------------------------------------------------- 263 Telephone in Housing Unit --------------------------------------- 264 Tenure ---------------------------------------------------------- 264 Type of Structure (See Units in Structure) Units in Structure ---------------------------------------------- 265 Usual Home Elsewhere -------------------------------------------- 266 Utilities ------------------------------------------------------- 267 Vacancy Status -------------------------------------------------- 267 Vacant Housing Units (See Living Quarters) Value ----------------------------------------------------------- 268 Vehicles Available ---------------------------------------------- 269 1 Page 168 ICPSR 6150 Year Householder Moved Into Unit -------------------------------- 270 Year Structure Built -------------------------------------------- 270 DERIVED MEASURES ------------------------------------------------ 271 Interpolation --------------------------------------------------- 271 Mean ------------------------------------------------------------ 272 Median ---------------------------------------------------------- 272 Percentages, Rates, and Ratios ---------------------------------- 272 Quartile -------------------------------------------------------- 272 1 ICPSR 6150 Page 169 POPULATION CHARACTERISTICS AGE The data on age were derived from answers to questionnaire item 5, which was asked of all persons. The age classification is based on the age of the person in complete years as of April 1, 1990. The age response in question 5a was used normally to represent a person's age. However, when the age response was unacceptable or unavailable, a person's age was derived from an acceptable year-of-birth response in question 5b. Data on age are used to determine the applicability of other questions for a person and to classify other characteristics in census tabulations. Age data are needed to interpret most social and economic characteristics used to plan and examine many programs and policies. Therefore, age is tabulated by single years of age and by marry different groupings, such as 5-year age groups. Some tabulations are shown by the age of the householder. These data were derived from the age responses for each householder. (For more information on householder, see the discussion under "Household Type and Relationship.") Median Age-This measure divides the age distribution into two equal parts: one-half of the cases falling below the median value and one-half above the value. Generally, median age is computed on the basis of more detailed age intervals than are shown in some census publications; thus, a median based on a less detailed distribution may differ slightly from a corresponding median for the same population based on a more detailed distribution. (For more information on medians, see the discussion under "Derived Measures.") Limitation of the Data - Counts in 1970 and 1980 for persons 100 years old and over were substantially overstated. Improvements were made in the questionnaire design, in the allocation procedures, and to the respondent instruction guide to attempt to minimize this problem for the 1990 census. Review of detailed 1990 census information indicated that respondents tended to provide their age as of the date of completion of the questionnaire, not their age as of April 1, 1990. In addition, there may have been a tendency for respondents to round their age up if they were close to having a birthday. It is likely that approximately 10 percent of persons in most age groups are actually 1 year younger. For most single years of age, the misstatements are largely offsetting. The problem is most pronounced at age 0 because persons lost to age 1 may not have been fully offset by the inclusion of babies born after April 1, 1990 and because there may have been more rounding up to age 1 to avoid reporting age as 0 years. (Age in complete months was not collected for infants under age 1.) 1 Page 170 ICPSR 6150 The reporting of age 1 year older than age on April 1, 1990 is likely to have been greater in areas where the census data were collected later in 1990. The magnitude of this problem was much less in the three previous censuses where age was typically derived from respondent data on year of birth and quarter of birth. (For more information on the design of the age question, see the section below that discusses "Comparability.") Comparability-Age data have been collected in every census. For the first time since 1950, the 1990 data are not available by quarter year of age. This change was made so that coded information could be obtained for both age and year of birth. In each census since 1940, the age of a person was assigned when it was not reported. In censuses before 1940, with the exception of 1880, persons of unknown age were shown as a separate category. Since 1960, assignment of unknown age has been performed by a general procedure described as "imputation." The specific procedures for imputing age have been different in each census. ANCESTRY The data on ancestry were derived from answers to questionnaire item 13, which was asked of a sample of persons. The question was based on self-identification; the data on ancestry represent self-classification by people according to the ancestry group(s) with which they most closely identify. Ancestry refers to a person's ethnic origin or descent, "roots," or heritage or the place of birth of the person or the person's parents or ancestors before their arrival in the United States. Some ethnic identities, such as "Egyptian" or "Polish" can be traced to geographic areas outside the United States, while other ethnicities such as "Pennsylvania Dutch" or "Cajun" evolved in the United States. The intent of the ancestry question was not to measure the degree of attachment the respondent had to a particular ethnicity. For example, a response of "Irish" might reflect total involvement in an "Irish" community or only a memory of ancestors several generations removed from the individual. The Census Bureau coded the responses through an automated review, edit, and coding operation. The open-ended write-in ancestry item was coded by subject-matter specialists into a numeric representation using a code list containing over 1,000 categories. The 1990 code list reflects the results of the Census Bureau's own research and consultations with many ethnic experts. Marry decisions were made to determine the classification of responses. These decisions affected the grouping of the tabulated data. For example, the "Assyrian" category includes both responses of "Assyrian" and "Chaldean." The ancestry question allowed respondents to report one or more ancestry groups. While a large number of respondents listed a single ancestry, the majority of answers included more than one ethnic entry. Generally, only the first two responses reported were coded in 1 ICPSR 6150 Page 171 1990. If a response was in terms of a dual ancestry, for example, Irish-English, the person was assigned two codes, in this case one for Irish and another for English. However, in certain cases, multiple responses such as "French Canadian," "Scotch-Irish," "Greek Cypriote," and "Black Dutch" were assigned a single code reflecting their status as unique groups. If a person reported one of these unique groups in addition to another group, for example, "Scotch-Irish English," resulting in three terms, that person received one code for the unique group ("Scotch-Irish") and another one for the remaining group ("English"). If a person reported "English Irish French," only English and Irish were coded. Certain combinations of ancestries where the ancestry group is a part of another, such as "GermanBavarian," the responses were coded as a single ancestry using the smaller group ('Bavarian"). Also, responses such as "Polish-American" or "Italian-American" were coded and tabulated as a single entry ("Polish" or "Italian"). The Census Bureau accepted "American" as a unique ethnicity if it was given alone, with an ambiguous response, or with State names. If the respondent listed any other ethnic identity such as "Italian American," generally the "American" portion of the response was not coded. However, distinct groups such as "American Indian," "Mexican American," and "African American" were coded and identified separately because they represented groups who considered themselves different from those who reported as "Indian," "Mexican," or "African," respectively. In all tabulations, when respondents provided an unacceptable ethnic identity (for example, an uncodeable or unintelligible response such as "multi-national," "adopted," or "I have no idea"), the answer was included in "Ancestry not reported." The tabulations on ancestry are presented Lising two types of data presentations-one used total persons as the base, and the other used total responses as the base. The following are categories shown in the two data presentations: Presentation Based on Persons: Single Ancestries Reported-includes all persons who reported only one ethnic group. Included in this category are persons with multiple-term responses such as "Scotch-Irish" who are assigned a single code. Multiple Ancestries Reported--Includes all per- sons who reported more than one group and were assigned two ancestry codes. Ancestry Unclassified-Includes all persons who provided a response that could not be assigned an ancestry code because they provided nonsensical 1 Page 172 ICPSR 6150 entries or religious responses. Presentations Based on Responses-. Total Ancestries Reported Includes the total num- ber of ancestries reported and coded. If a person reported a multiple ancestry such as "French Danish," that response was counted twice in the tabulations-once in the "French" category and again in the "Danish" category. Thus, the sum of the counts in this type of presentation is not the total population but the total of all responses. First Ancestry Reported-includes the first response of all persons who reported at least one codeable entry. For example, in this category, the count for "Danish" would include all those who reported only Danish and those who reported Danish first and then some other group. Second Ancestry Reported-Includes the second response of all persons who reported a multiple ancestry. Thus, the count for "Danish" in this category includes all persons who reported Danish as the second response, regardless of the first response provided. The Census Bureau identified hundreds of ethnic groups in the 1990 census. However, it was impossible to show information for every group in all census tabulations because of space constraints. Publications such as the 1990 CP-2, Social and Economic Characteristics and the 1990 CPH-3, Population and Housing Characteristics for Census Tracts and Block Numbering Areas reports show a limited number of groups based on the number reported and the advice received from experts. A more complete distribution of groups is presented in the 1990 Summary Tape File 4, Supplementary Reports, and a special subject report on ancestry. In addition, groups identified specifically in the questions on race and Hispanic origin (for example, Japanese, Laotian, Mexican, Cuban, and Spaniard), in general, are not shown separately in ancestry tabulations. Limitation of the Data-Although some experts consider religious affiliation a component of ethnic identity, the ancestry question was not designed to collect any information concerning religion. The Bureau of the Census is prohibited from collecting information on religion. Thus, if a religion was given as an answer to the ancestry question, it was coded as an "Other" response. Comparability - A question on ancestry was first asked in the 1980 census. Although there were no comparable data prior to the 1980 census, related information on ethnicity was collected through questions on parental birthplace, own birthplace, and language which were included in previous censuses. Unlike other census questions, 1 ICPSR 6150 Page 173 there was no imputation for nonresponse to the ancestry question. In 1990, respondents were allowed to report more than one ancestry group; however, only the first two ancestry groups identified were coded. In 1980, the Census Bureau attempted to code a third ancestry for selected triple-ancestry responses. New categories such as "Arab" and "West Indian" were added to the 1990 question to meet important data needs. The "West Indian" category excluded "Hispanic" groups such as "Puerto Rican" and "Cuban" that were identified primarily through the question on Hispanic origin. In 1990, the ancestry group, "American" is recognized and tabulated as a unique ethnicity. In 1980, "American" was tabulated but included under the category "Ancestry not specified." A major improvement in the 1990 census was the use of an automated coding system for ancestry responses. The automated coding system used in the 1990 census greatly reduced the potential for error associated with a clerical review. Specialists with a thorough knowledge of the subject matter reviewed, edited, coded, and resolved inconsistent or incomplete responses. CITIZENSHIP The data on citizenship were derived from answers to questionnaire item 9, which was asked of a sample of persons. Citizen-Persons who indicated that they were native-born and foreign-born persons who indicated that they have become naturalized. (For more information on native and foreign born, see the discussion under "Place of Birth.") There are four categories of citizenship: (1) born in the United States, (2) born in Puerto Rico, Guam, the Virgin Islands of the United States, or the Commonwealth of the Northern Mariana Islands, (3) born abroad of American parents, and (4) citizen by naturalization. Naturalized Citizen-Foreign-born persons who had completed the naturalization process at the time of the census and upon whom the rights of citizenship had been conferred. Not a Citizen-Foreign-born persons who were not citizens, including persons who had begun but not completed the naturalization process at the time of the census. Limitation of the Data-Evaluation studies completed after previous censuses indicated that some persons may have reported themselves as citizens although they had not yet attained the status. 1 Page 174 ICPSR 6150 Comparability-Similar questions on citizenship were asked in the censuses of 1820, 1830, 1870, 1890 through 1950, 1 970, and 1980. The 1980 question was asked of a sample of the foreign-born population. In 1990, both native and foreign-born persons who received the long-form questionnaire were asked to respond to the citizenship question. EDUCATIONAL ATTAINMENT Data on educational attainment were derived from answers to questionnaire item 12, which was asked of a sample of persons. Data are tabulated as attainment for persons 15 years old and over. Persons are classified according to the highest level of school completed or the highest degree received. The question included instructions to report the level of the previous grade attended or the highest degree received for persons currently enrolled in school. The question included response categories which allowed persons to report completing the 12th grade without receiving a high school diploma, and which instructed respondents to report as "high school graduate(s)"-persons who received either a high school diploma or the equivalent, for example, passed the Test of General Educational Development (G.E.D.), and did not attend college. (On the Military Census Report questionnaire, the lowest response category was "Less than 9th grade.") Instructions included in the 1990 respondent instruction guide, which was mailed with the census questionnaire, further specified that schooling completed in foreign or ungraded school systems should be reported as the equivalent level of schooling in the regular American system; that vocational certificates or diplomas from vocational, trade, or business schools or colleges were not to be reported unless they were college level degrees; and that honorary degrees were not to be reported. The instructions gave "medicine, dentistry, chiropractic, optometry, osteopathic medicine, pharmacy, podiatry, veterinary medicine, law, and theology" as examples of professional school degrees, and specifically excluded "barber school, cosmetology, or other training for a specific trade" from the professional school category. The order in which they were listed suggested that doctorate degrees were "higher" than professional school degrees, which were "higher" than master's degrees. Persons who did not report educational attainment were assigned the attainment of a person of the same age, race or Spanish origin, and sex who resided in the same or a nearby area. Persons who filled more than one circle were edited to the highest level or degree reported. High School Graduate or Higher-Includes per- sons whose highest degree was a high school diploma or its equivalent, persons who attended college or professional school, and persons who received a college, university, or professional degree. 1 ICPSR 6150 Page 175 Persons who reported completing the 12th grade but not receiving a diploma are not included. Not Enrolled, Not High School Graduate-Includes persons of compulsory school attendance age or above who were not enrolled in school and were not high school graduates; these persons may be taken to be "high school dropouts." There is no restriction on when they "dropped out of school, and they may have never attended high school. In prior censuses, "Median school years completed" was used as a summary measure of educational attainment. In 1990, the median can only be calculated for groups of which less than half the members have attended college. "Percent high school graduate or higher" and "Percent bachelors degree or higher" are summary measures which can be calculated from the present data and offer quite readily interpretable measures of differences between population subgroups. To make comparisons over time, "Percent high school graduate or higher". can be calculated and "Percent bachelor's degree or higher" can be approximated with data from previous censuses. Comparability-From 1840 to 1930, the census measured educational attainment by means of a basic literacy question. In 1940, a single question was asked on highest grade of school completed. In the censuses of 1950 through 1980, a two-part question asking highest grade of school attended and whether that grade was finished was used to construct highest grade or year of school completed. For persons who have not attended college, the response categories in the 1990 educational attainment question should produce data which are comparable to data on highest grade completed from earlier censuses. The response categories for persons who have attended college were modified from earlier censuses because there was some ambiguity in interpreting responses in terms of the number of years of college completed. For instance, it was not clear whether "completed the fourth year of college," "completed the senior year of college," and "college graduate" were synonomous. Research conducted shortly before the census suggests that these terms were more distinct in 1990 than in earlier decades, and this change may have threatened the ability to estimate the number of "College graduates" from the number of persons reported as having completed the fourth or a higher year of college. It was even more difficult to make inferences about post-baccalaureate degrees and "Associate" degrees from highest year of college completed. Thus, comparisons of post-secondary educational attainment in this and earlier censuses should be made with great caution. In the 1960 and subsequent censuses, persons for whom educational attainment was not reported were assigned the same attainment level as a similar person whose residence was in the same or a nearby area. 1 Page 176 ICPSR 6150 In the 1940 and 1950 censuses, persons for whom educational attainment was not reported were not allocated. EMPLOYMENT STATUS The data on employment status were derived from answers to questionnaire items 21, 25, and 26, which were asked of a sample of persons. The series of questions on employment status was asked of all persons 15 years old and over and was designed to identify, in this sequence: (1) persons who worked at any time during the reference week; (2) persons who did not work during the reference week but who had jobs or businesses from which they were temporarily absent (excluding layoff); (3) persons on layoff; and (4) persons who did not work during the reference week, but who were looking for work during the last four weeks and were available for work during the reference week. (For more information, see the discussion under "Reference Week.") The employment status data shown in this and other 1990 census tabulations relate to persons 16 years old and over. Some tabulations showing employment status, however, include persons 15 years old By definition, these persons are classified as "Not in Labor Force.". In the 1940,1950, and 1960 censuses, employment status data were presented for persons 14 years old and over. The change in the universe was made in 1 970 to agree with the official measurement of the labor force as revised in January 1967 by the U.S. Department of Labor. The 1970 census was the last to show employment data for persons 14 and 15 years old. Employed-All civilians 16 years old and over who were either (1) "at work"-those who did any work at all during the reference week as paid employees, worked in their own business or profession, worked on their own farm, or worked 15 hours or more as unpaid workers on a family farm or in a family business; or (2) were "with a job but not at work" -those who did not work during the reference week but had jobs or businesses from which they were temporarily absent due to illness, bad weather, industrial dispute, vacation, or other personal reasons. Excluded from the employed are persons whose only activity consisted of work around the house or unpaid volunteer work for religious, charitable, and similar organizations; also excluded are persons on active duty in the United States Armed Forces. Unemployed-All civilians 16 years old and over are classified as unemployed if they (1) were neither "at work" nor "with a job but not at work" during the reference week, and (2) were looking for work during the last 4 weeks, and (3) were available to accept a job. Also included as unemployed are civilians who did not work at all during the reference week and were waiting to be called back to a job from which they had been laid off. Examples of job seeking activities are: * Registering at a public or private employment office 1 ICPSR 6150 Page 177 * Meeting with prospective employers * Investigating possibilities for starting a professional practice or opening a business * Placing or answering advertisements * Writing letters of application * Being on a union or professional register Civilian Labor Force-Consists of persons classified as employed or unemployed in accordance with the criteria described above. Experienced Unemployed-These are unemployed persons who have worked at any time in the past. Experienced Civilian Labor Force-Consists of the employed and the experienced unemployed. Labor Force-All persons classified in the civilian labor force plus members of the U.S. Armed Forces (persons on active duty with the United States Army, Air Force, Navy, Marine Corps, or Coast Guard). Not in Labor Force-All persons 16 years old and over who are not classified as members of the labor force. This category consists mainly of students, housewives, retired workers, seasonal workers enumerated in an off season who were not looking for work, institutionalized persons, and persons doing only incidental unpaid family work (less than 15 hours during the reference week). Worker-This term appears in connection with several subjects: journey-to-work items, class of worker, weeks worked in 1989, and number of workers in family in 1989. Its meaning varies and, therefore, should be determined in each case by referring to the definition of the subject in which it appears. Actual Hours Worked Last Week-All persons who reported working during the reference week were asked to report in questionnaire item 21 b the number of hours that they worked. The statistics on hours worked pertain to the number of hours actually worked at all jobs, and do not necessarily reflect the number of hours typically or usually worked or the scheduled number of hours. The concept of "actual hours" differs from that of "usual hours" described below. The number of persons who worked only a small number of hours is probably understated since such persons sometimes consider themselves as not working Respondents were asked to include overtime or extra hours worked, but to exclude lunch hours, sick leave, and vacation leave. Limitation of the Data-The census may understate the number of employed persons because persons who have irregular, casual, or unstructured jobs sometimes report themselves as not working. The number of employed persons "at work" is probably overstated in the 1 Page 178 ICPSR 6150 census (and conversely, the number of employed "with a job, but not at work" is understated) since some persons on vacation or sick leave erroneously reported themselves as working. This problem has no effect on the total number of employed persons. The reference week for the employment data is not the same for all persons. Since persons can change their employment status from one week to another, the lack of a uniform reference week may mean that the employment data do not reflect the reality of the employment situation of any given week. (For more information, see the discussion under "Reference Week.") Comparability-The questionnaire items and employment status concepts for the 1990 census are essentially the same as those used in the 1980 and 1970 censuses. However, these concepts differ in many respects from those associated with the 1950 and 1960 censuses. Since employment data from the census are obtained from respondents in households, they differ from statistics based on reports from individual business establishments, farm enterprises, and certain government programs. Persons employed at more than one job are counted only once in the census and are classified according to the job at which they worked the greatest number of hours during the reference week. In statistics based on reports from business and farm establishments, persons who work for more than one establishment may be counted more than once. Moreover, some tabulations may exclude private household workers, unpaid family workers, and self-employed persons, but may include workers less than 16 years of age. An additional difference in the data arises from the fact that persons who had a job but were not at work are included with the employed in the census statistics, whereas many of these persons are likely to be excluded from employment figures based on establishment payroll reports. Furthermore, the employment status data in census tabulations include persons on the basis of place of residence regardless of where they work, whereas establishment data report persons at their place of work regardless of where they live. This latter consideration is particularly significant when comparing data for workers who commute between areas. Census data on actual hours worked during the reference week may differ from data from other sources. The census measures hours actually worked, whereas some surveys measure hours paid for by employers. Comparability of census actual hours worked data may also be affected by the nature of the reference week (see "Reference Week"). For several reasons, the unemployment figures of the Census Bureau are not comparable with published figures on unemployment compensation claims. For example, figures on unemployment compensation claims exclude persons who have exhausted their benefit rights, new workers who have not earned rights to unemployment 1 ICPSR 6150 Page 179 insurance, and persons losing jobs not covered by unemployment insurance systems (including some workers in agriculture, domestic services, and religious organizations, and self-employed and unpaid family workers). In addition, the qualifications for drawing unemployment compensation differ from the definition of unemployment used by the Census Bureau. Persons working only a few hours during the week and persons with a job but not at work are sometimes eligible for unemployment compensation but are classified as "Employed" in the census. Differences in the geographical distribution of unemployment data arise because the place where claims are filed may not necessarily be the same as the place of residence of the unemployed worker. The figures on employment status from the decennial census are generally comparable with similar data collected in the Current Population Survey. However, some difference may exist because of variations in enumeration and processing techniques. FERTILITY The data on fertility (also referred to as "children ever born") were derived from answers to questionnaire item 20, which was asked of a sample of women 15 years old and over regardless of marital status. Stillbirths, stepchildren, and adopted children were excluded from the number of children ever born. Ever-married women were instructed to include all children born to them before and during their most recent marriage, children no longer living, and children away from home, as well as children who were still living in the home. Never- married women were instructed to include all children born to them. Data are most frequently presented in terms of the aggregate number of children ever born to women in the specified category and in terms of the rate per 1,000 women. For purposes of calculating the aggregate, the open-ended response category, "12 or more" is assigned a value of 13. Limitation of the Data-Although the data are assumed to be less complete for out-of-wedlock births than for births occurring within marriage, comparisons of 1980 census data on the fertility of single women with other census sources and administrative records indicate that no significant differences were found between different data sources; that is, 1980 census data on children ever born to single women were complete with no significant understatements of childbearing. Comparability-The wording of the question on children ever born was the same in 1990 as in 1980. In 1970, however, the question on children ever born was asked of all ever-married women but only of never married women who received self-administered questionnaires. Therefore, rates and numbers of children ever born to single women in 1970 may be understated. Data presented for children ever born to 1 Page 180 ICPSR 6150 ever-married women are comparable for the 1990 census and all previous censuses containing this question. GROUP QUARTERS All persons not living in households are classified by the Census Bureau as living in group quarters. Two general categories of persons in group quarters are recognized: (1) institutionalized persons and (2) other persons in group quarters (also referred to as "noninstitutional group quarters"). Institutionalized Persons-includes persons under formally authorized, supervised care or custody in institutions at the time of enumeration. Such persons are classified as "patients or inmates" of an institution regardless of the availability of nursing or medical care, the length of stay, or the number of persons in the institution. Generally, institutionalized persons are restricted to the institutional buildings and grounds (or must have passes or escorts to leave) and thus have limited interaction with the surrounding community. Also, they are generally under the care of trained staff who have responsibility for their safekeeping and supervision. Type of Institution-The type of institution was determined as part of census enumeration activities. For institutions which specialize in only one specific type of service, all patients or inmates were given the same classification. For institutions which had multiple types of major services (usually general hospitals and Veterans' Administration hospitals), patients were classlied according to selected types of wards. For example, in psychiatric wards of hospitals, patients were classified in "mental (psychiatric) hospitals"; in hospital wards for persons with chronic diseases, patients were classified in "hospitals for the chronically ill." Each patient or inmate was classified in only one type of institution. Institutions include the following types: Correctional Institutions-Includes prisons, Federal detention centers, military stockades and jails, police lockups, halfway houses, local jails, and other con- finement facilities, including work farms. Prisons-Where persons convicted of crimes serve their sentences. In some census products, the prisons are classified by two types of control: (1) "Federal" (operated by the Bureau of Prisons of the Department of Justice) and (2) "State." Residents who are criminally insane were classi- fied on the basis of where they resided at the time of enumeration: (1) in institutions (or hospital wards) operated by departments of correction or similar agencies; or (2) in institutions operated by depart- 1 ICPSR 6150 Page 181 ments of mental health or similar agencies. Federal Detention Centers-Operated by the Immi- gration and Naturalization Service (INS) and the Bureau of Prisons. These facilities include deten- tion centers used by the Park Police; Bureau of Indian Affairs Detention Centers; INS Centers, such as the INS Federal Alien Detention Facility; INS Processing Centers; and INS Contract Deten- tion Centers used to detain aliens under exclusion or deportation proceedings, as well as those aliens who have not been placed into proceedings, such as custodial required departures; and INS Deten- tion Centers operated within local jails, and State and Federal prisons. Military Stockades, Jails-Operated by military police and used to hold persons awaiting trial or con- victed of violating military laws. Local Jails and Other Confinement Facilities-In- cludes facilities operated by counties and cities that primarily hold persons beyond arraignment, usually for more than 48 hours. Also included in this category are work farms used to hold persons awaiting trial or serving time on relatively short sentences and jails run by private businesses under contract for local governments (but not by State governments). Police Lockups-Temporary-holding facilities oper- ated by county and city police that hold persons for 48 hours or less only if they have not been formally charged in court. Halfway Houses-Operated for correctional pur- poses and include probation and restitution cen- ters, pre-release centers, and community-residential centers. Other Types of Correctional Institutions-Privately operated correctional facilities and correctional facilities specifically for alcohol/drug abuse. Nursing Homes-Comprises a heterogeneous group of places. The majority of patients are elderly, although persons who require nursing care because of chronic physical conditions may be found in these homes regardless of their age. Included in this category are skilled-nursing facilities, intermediate-care facilities, 1 Page 182 ICPSR 6150 long-term care rooms in wards or buildings on the grounds of hospitals, or long-term care rooms/ nurs- ing wings in congregate housing facilities. Also included are nursing convalescent, and rest homes, such as soldiers', sailors', veterans', and fraternal or religious homes for the aged, with or without nursing care. In some census products, nursing homes are classified by type of ownership as "Federal," "State," "Private not-for-profit," and "Private for profit." Mental (Psychiatric) Hospitals-Includes hospitals or wards for the criminally insane not operated by a prison, and psychiatric wards of general hospitals and veterans' hospitals. Patients receive supervised medical/nursing care from formally-trained staff. In some census products, mental hospitals are classi- fied by type of ownership as "Federal," "State or local", "Private," and "Ownership not known." Hospitals for Chronically Ill-Includes hospitals for patients who require long-term care, including those in military hospitals and wards for the chronically ill located on military bases; or other hospitals or wards for the chronically ill, which include tuberculosis hospitals or wards, wards in general and Veterans' Administration hospitals for the chronically ill, neuro- logical wards, hospices, wards for patients with Hans- en's Disease (leprosy) and other incurable diseases, and other unspecified wards for the chronically ill. Patients who had no usual home elsewhere were enumerated as part of the institutional population in the wards of general and military hospitals. Most hospital patients are at the hospital temporarily and were enumerated at their usual place of residence. (For more information, see "Wards in General and Military Hospitals for Patients Who Have No Usual Home Elsewhere.") Schools, Hospitals, or Wards for the Mentally Retard ed-Includes those institutions such as wards in hospitals for the mentally retarded, and intermediate- care facilities for the mentally retarded that provide supervised medical/ nursing care from formally-trained staff. In some census products, this category is classified by type of ownership as "Federal," "State or local," "Private," and "Ownership not known." Schools, Hospitals, or Wards for the Physically Hand- icapped-Includes three types of institutions: institu- tions for the blind, those for the deaf, and orthopedic wards and institutions for the physically handicapped. 1 ICPSR 6150 Page 183 Institutions for persons with speech problems are classified with "institutions for the deaf." The cate- gory "orthopedic wards and institutions for the phys- ically handicapped" includes those institutions pro- viding relatively long-term care to accident victims, and to persons with polio, cerebral palsy, and mus- cular dystrophy. In some census products, this cate- gory is classified by type of ownership as "Public," "Private," and "Ownership not known." Hospitals, and Wards for Drug/Alcohol Abuse-in- cludes hospitals, and hospital wards in psychiatric and general hospitals. These facilities are equipped medically and designed for the diagnosis and treat- ment of medical or psychiatric illnesses associated with alcohol or drug abuse. Patients receive super- vised medical care from formally-trained staff. Wards in General and Military Hospitals for Patients Who Have No Usual Home Elsewhere-includes maternity, neonatal, pediatric (including wards for boarder babies), military, and surgical wards of hos- pitals, and wards for persons with infectious dis- eases. Juvenile Institutions-includes homes, schools, and other institutions providing care for children (short-or long-term care). Juvenile institutions include the fol- lowing types: Homes for Abused, Dependent, and Neglected Children-includes orphanages and other institu- tions which provide long-term care (usually more than 30 days) for children. This category is classi- fied in some census products by type of ownership as "Public" and "Private." Residential Treatment Centers-Includes those institutions which primarily serve children who, by clinical diagnosis, are moderately or seriously dis- turbed emotionally. Also, these institutions provide long-term treatment services, usually supervised or directed by a psychiatrist. Training Schools for Juvenile Delinquents-Includes residential training schools or homes, and indus- trial schools, camps, or farms for juvenile delin- quents. Public Training Schools for Juvenile Delinquents- Usually operated by a State agency (for exam- 1 Page 184 ICPSR 6150 ple, department of welfare, corrections, or a youth authority). Some are operated by county and city governments. These public training schools are specialized institutions serving delin- quent children, generally between the ages of 10 and 17 years old, all of whom are committed by the courts. Private Training Schools-Operated under pri- vate auspices. Some of the children they serve are committed by the courts as delinquents. Others are referred by parents or social agen- cies because of delinquent behavior. One dif- ference between private and public training schools is that, by their administrative policy, private schools have control over their selection and intake. Detention Centers-includes institutions providing short-term care (usually 30 days or less) primarily for delinquent children pending disposition of their cases by a court. This category also covers diag- nostic centers. In practice, such institutions may be caring for both delinquent and neglected chil- dren pending court disposition. Other Persons in Group Quarters (also referred to as "noninstitutional group quarters")-includes all persons who live in group quarters other than institutions. Persons who live in the following living quarters are classified as "other persons in group quarters" when there are 10 or more unrelated persons living in the unit; otherwise, these living quarters are classified as housing units, Rooming Houses-Includes persons residing in room- ing and boarding houses and living in quarters with 10 or more unrelated persons. Group Homes-Includes "community-based homes" that provide care and supportive services. Such places include homes for the mentally ill, mentally retarded, and physically handicapped; drug/ alcohol halfway houses; communes; and maternity homes for unwed mothers. Homes for the Mentally Ill-Includes community- based homes that provide care primarily for the mentally ill. In some data products, this category is classified by type of ownership as "Federal," "State ... .. Private," and "Ownership not known." Homes which combine treatment of the physically 1 ICPSR 6150 Page 185 handicapped with treatment of the mentally ill are counted as homes for the mentally ill. Homes for the Mentally Retarded Includes community- based homes that provide care primarily for the mentally retarded. Homes which combine treat- ment of the physically handicapped with treatment of the mentally retarded are counted as homes for the mentally retarded. This category is classified by type of ownership in some census products, as "Federal," "State," "Private," or "Ownership not known." Homes for the Physically Handicapped-Includes community-based homes for the blind, for the deaf, and other community-based homes for the physically handicapped. Persons with speech prob- lems are classified with homes for the deaf. In some census products, this category is classified by type of ownership as "Public," "Private," or "Ownership not known." Homes or Halfway Houses for Drug/Alcohol Abuse --In- cludes persons with no usual home elsewhere in places that provide community-based care and supportive services to persons suffering from a drug/alcohol addiction and to recovering alcohol- ics and drug abusers. Places providing community- based care for drug and alcohol abusers include group homes, detoxification centers, quarterway houses (residential treatment facilities that work closely with accredited hospitals), halfway houses, and recovery homes for ambulatory, mentally com- petent recovering alcoholics and drug abusers who may be re-entering the work force. Maternity Homes for Unwed Mothers-Includes persons with no usual home elsewhere in places that provide domestic care for unwed mothers and their children. These homes may provide social services and post-natal care within the facility, or may make arrangements for women to receive such services in the community. Nursing services are usually available in the facility. Other Group Homes-Includes persons with no usual home elsewhere in communes, foster care homes, and job corps centers with 10 or more unrelated persons. These types of places provide communal living quarters, generally for persons who have formed their own community in which 1 Page 186 ICPSR 6150 they have common interests and often share or own property jointly. Religious Group Quarters-Includes, primarily, group quarters for nuns teaching in parochial schools and for priests living in rectories. It also includes other convents and monasteries, except those associated with a general hospital or an institution. College Quarters Off Campus-includes privately- owned rooming and boarding houses off campus, if the place is reserved exclusively for occupancy by college students and if there are 10 or more unre- lated persons. In census products, persons in this category are classified as living in a college dormi- tory. Persons residing in certain other types of living arrangements are classified as living in "noninstitutional group quarters" regardless of the number of people sharing the unit. These include persons residing in the following types of group quarters: College Dormitories-Includes college students in dormitories (provided the dormitory is restricted to students who do not have their families living with them), fraternity and sorority houses, and on-campus residential quarters used exclusively for those in religious orders who are attending college. Students in privately-owned rooming and boarding houses off campus are also included, if the place is reserved exclusively for occupancy by college-level students and if there are 10 or more unrelated persons. Military Quarters-Includes military personnel living in barracks and dormitories on base, in transient quarters on base for temporary residents (both civil- ian and military), and on military ships. However, patients in military hospitals receiving treatment for chronic diseases or who had no usual home else- where, and persons being held in military stockades were included as part of the institutional population. Agriculture Workers' Dormitories-Includes persons in migratory farm workers' camps on farms, bunk- houses for ranch hands, and other dormitories on farms, such as those on "tree farms." Other Workers' Dormitories-Includes persons in log- ging camps, construction workers' camps, firehouse dormitories, job-training camps, energy enclaves (Alaska only), and nonfarm migratory workers' camps (for 1 ICPSR 6150 Page 187 example, workers in mineral and mining camps). Emergency Shelters for Homeless Persons (with sleeping facilities) and Visible in Street Location- Includes persons enumerated during the "Shelter- and-Street-Night" operation primarily on March 20-21, 1990. Enumerators were instructed not to ask if a person was "homeless." If a person was at one of the locations below on March 20-21, the person was counted as described below. (For more information on the "Shelter-and-Street-Night" operation, see Appen- dix D, Collection and Processing Procedures.) This category is divided into four classifications: Emergency Shelters for Homeless Persons (with sleeping facilities-includes persons who stayed overnight on March 20, 1990, in permanent and temporary emergency housing, missions, hotels/ motels, and flophouses charging $12 or less (exclud- ing taxes) per night; Salvation Army shelters, hotels, and motels used entirely for homeless persons regardless of the nightly rate charged; rooms in hotels and motels used partially for the homeless; and similar places known to have persons who have no usual home elsewhere staying overnight. If not shown separately, shelters and group homes that provide temporarily sleeping facilities for run- away, neglected, and homeless children are included in this category in data products. Shelters for Runaway, Neglected, and Homeless Children-Includes shelters/group homes which provide temporarily sleeping facilities for juveniles. Visible in Street Locations-Includes street blocks and open public locations designated before March 20,1990 by city and community officials as places where the homeless congregate at night. All persons found at predesignated street sites from 2 a.m. to 4 a.m. and leaving abandoned or boarded-up buildings from 4 am. to 8 a.m. on March 21, 1990 were enumerated during "street" enumeration, except persons in uniform such as police and persons engaged in obvious money- making activities other than begging or panhan- dling Enumerators were instructed not to ask if a person was "homeless." This cannot be considered a complete count of all persons living on the streets because those who were so well hidden that local people did not know where to find them were likely to have been 1 Page 188 ICPSR 6150 missed as were persons moving about or in places not identified by local officials. It is also possible that persons with homes could have been included in the count of "visible in street locations" if they were present when the enumerator did the enu- meration of a particular block. Predesignated street sites include street cor- ners, parks, bridges, persons emerging from aban- doned and boarded-up buildings, noncommercial campsites (tent cities), all-night movie theaters, all-night restaurants, emergency hospital waiting rooms, train stations, airports, bus depots, and subway stations. Shelters for Abused Women (Shelters Against Domestic Violence or Family Crisis Centers)- Includes community-based homes or shelters that provide domiciliary care for women who have sought shelter from family violence and who may have been physically abused. Most shelters also provide care for children of abused women. These shelters may provide social services, meals, psy- chiatric treatment, and counseling. In some cen- sus products, "shelters for abused women" are included in the category "other noninstitutional group quarters." Dormitories for Nurses and Interns in General and Military Hospitals-Includes group quarters for nurses and other staff members. It excludes patients. Crews of Maritime Vessels-Includes officers, crew members, and passengers of maritime U.S. flag vessels. All ocean-going and Great Lakes ships are included. Staff Residents of Institutions Includes staff resid- ing in group quarters on institutional grounds who provide formally-authorized, supervised care or cus- tody for the institutionalized population. Other Nonhousehold Living Situations-Includes per- sons with no usual home elsewhere enumerated during transient or "T-Night" enumeration at YMCA's, YWCA's, youth hostels, commercial and government- run campgrounds, campgrounds at racetracks, fairs, and carnivals, and similar transient sites. Living Quarters for Victims of Natural Disasters-in- cludes living quarters for persons temporarily dis- 1 ICPSR 6150 Page 189 placed by natural disasters. Limitation of the Data-Two types of errors can occur in the classification of "types of group quarters": 1. Misclassification of Group Quarters-During the 1990 Special Place Prelist operation, the enumera- tor determined the type of group quarters associ- ated with each special place in their assignment. The enumerator used the Alphabetical Group Quar- ters Code List and Index to the Alphabetical Group Quarters Code List to assign a two-digit code number followed by either an "I," for institutional, or an "N," for noninstitutional to each group quarters. In 1990, unacceptable group quarter codes were edited. 2. No Classification (unknowns)-The imputation rate for type of institution was higher in 1980 (23.5 percent) than in 1970 (3.3 percent). Improvements were made to the 1990 Alphabetical Group Quar- ters Code List; that is, the inclusion of more group quarters categories and an "Index to the Alphabet- ical Group Quarters Code List." (For more informa- tion on the allocation rates for Type of Institution, see the allocation rates in 1990 CP-1, General Population Characteristics) In previous censuses, allocation rates for demographic characteristics (such as age, sex, race, and marital status) of the institutional population were similar to those for the total population. The allocation rates for sample characteristics such as school enrollment, highest grade completed, income, and veteran status for the institutional and noninstitutional group quarters population have been substantially higher than the population in households at least as far back as the 1960 census. The data, however, have historically presented a reasonable picture of the institutional and noninstitutional group quarters population. Shelter and Street, Night (S-Night)-For the 1990 census "Shelter-and-Street-Night" operation, persons well hidden, moving about, or in locations enumerators did not visit were likely to be missed. The number of people missed will never be known; thus, the 1990 census cannot be considered to include a definitive count of America's total homeless population. It does, however, give an idea of relative differences among areas of the country. Other components were counted as part of regular census procedures. The count of persons in shelters and visible on the street could have been affected by many factors. How much the factors affected the count can never be answered definitively, but some elements include: 1 Page 190 ICPSR 6150 1. How well enumerators were trained and how well they followed procedures. 2. How well the list of shelter and street locations given to the Census Bureau by the local govern- ment reflected the actual places that homeless persons stay at night. 3. Cities were encouraged to open temporary shelters for census night, and many did that and actively encouraged people to enter the shelters. Thus, people who may have been on the street otherwise were in shelters the night of March 20, so that the ratio of shelter-to-street population could be differ- ent than usual. 4. The weather, which was unusually cold in some parts of the country, could affect how likely people were to seek emergency shelter or to be more hidden than usual if they stayed outdoors. 5. The media occasionally interfered with the ability to do the count. 6. How homeless people perceived the census and whether they wanted to be counted or feared the census and hid from it. The Census Bureau conducted two assessments of Shelter and Street Night: (1) the quality of the lists of shelter's used for the Shelter-and-Street-Night operation, and (2) how well procedures were followed by censustakers for the street count in parts of five cities (Chicago, Los Angeles, New Orleans, New York, and Phoenix). Information about these two assessments is available from the Chief, Center for Survey Methods Research, Bureau of the Census, Washington, DC 20233. Comparability-For the 1990 census, the definition of institutionalized persons was revised so that the definition of "care" only includes persons under organized medical or formally-authorized, supervised care or custody. As a result of this change to the institutional definition, maternity homes are classified as noninstitutional rather than institutional group quarters as in previous censuses. The following types of other group quarters are classified as institutional rather than noninstitutional group quarters: "halfway houses (operated for correctional purposes)" and "wards in general and military hospitals for patients who have no usual home elsewhere," which includes maternity, neonatal, pediatric, military, and surgical wards of hospitals, other purpose wards of hospitals, and wards for infectious diseases. These changes should not significantly affect the comparability of data with earlier 1 ICPSR 6150 Page 191 censuses because of the relatively small number of persons involved. As in 1980, 10 or more unrelated persons living together were classified as living in noninstitutional group quarters. In 1970, the criteria was six or more unrelated persons. Several changes also have occurred in the identification of specific types of group quarters. For the first time, the 1990 census identifies separately the following types of correctional institutions: persons in halfway houses (operated for correctional purposes), military stockades and jails, and police lockups. In 1990, tuberculosis hospitals or wards are included with hospitals for the chronically ill; in 1980, they were shown separately. For 1990, the noninstitutional group quarters category, "Group homes" is further classified as: group homes for drug/ alcohol abuse; maternity homes (for unwed mothers), group homes for the mentally ill, group homes for the mentally retarded, and group homes for the physically handicapped. Persons living in communes, fostercare homes, and job corps centers are classified with "Other group homes" only if 10 or more unrelated persons share the unit; otherwise, they are classified as housing units. In 1990, workers' dormitories were classified as group quarters regardless of the number of persons sharing the dorm. In 1980, 10 or more unrelated persons had to share the dorm for it to be classified as a group quarters. In 1960, data on persons in military barracks were shown only for men. In subsequent censuses, they include both men and women. In 1990 census data products, the phrase "inmates of institutions" was changed to "institutionalized persons." Also, persons living in noninstitutional group quarters were referred to as "other persons in group quarters," and the phrase "staff residents" was used for staff living in institutions. In 1990, there are additional institutional categories and noninstitutional group quarters categories compared with the 1980 census. The institutional categories added include "hospitals and wards for drug/alcohol abuse" and "military hospitals for the chronically ill." The noninstitutional group quarters categories added include emergency shelters for homeless persons; shelters for runaway, neglected, and homeless children; shelters for abused women; and visible-in-street locations. Each of these noninstitutional group quarters categories was enumerated on March 20-21, 1990, during the "Shelter-and-Street-Night" operation, (For more information on the "Shelter-and-Street-Night" operation, see Appendix D, Collection and Processing Procedures.) HISPANIC ORIGIN The data on Spanish/ Hispanic origin were derived from answers to 1 Page 192 ICPSR 6150 questionnaire item 7, which was asked of all persons. Persons of Hispanic origin are those who classified themselves in one of the specific Hispanic origin categories listed on the questionnaire-"Mexican," "Puerto Rican," or "Cuban"-as well as those who indicated that they were of "other Spanish/Hispanic" origin. Persons of "Other Spanish/Hispanic" origin are those whose origins are from Spain, the Spanish-speaking countries of Central or South America, or the Dominican Republic, or they are persons of Hispanic origin identifying themselves generally as Spanish, Spanish-American, Hispanic, Hispano, Latino, and so on. Write-in responses to the "other Spanish/Hispanic" category were coded only for sample data. Origin can be viewed as the ancestry, nationality group, lineage, or country of birth of the person or the person's parents or ancestors before their arrival in the United States. Persons of Hispanic origin may be of any race. Some tabulations are shown by the Hispanic origin of the householder. In all cases where households, families, or occupied housing units are classified by Hispanic origin, the Hispanic origin of the householder is used. (See the discussion of householder under "Household Type and Relationship.") During direct interviews conducted by enumerators, if a person could not provide a single origin response, he or she was asked to select, based on self-identification, the group which best described his or her origin or descent. If a person could not provide a single group, the origin of the person's mother was used. If a single group could not be provided for the person's mother, the first origin reported by the person was used. If any household member failed to respond to the Spanish/Hispanic origin question, a response was assigned by the computer according to the reported entries of other household members by using specific rules of precedence of household relationship. In the processing of sample questionnaires, responses to other questions on the questionnaire, such as ancestry and place of birth, were used to assign an origin before any reference was made to the origin reported by other household members. If an origin was not entered for any household member, an origin was assigned from another household according to the race of the householder. Comparability-There may be differences between the total Hispanic origin population based on 100-percent tabulations and sample tabulations. Such differences are the result of sampling variability, nonsampling error, and more extensive edit procedures for the Spanish/ Hispanic origin item on the sample questionnaires. The 1990 data on Hispanic origin are generally comparable with those for the 1980 census. However, there are some differences in the format of the Hispanic origin question between the two censuses. For 1 ICPSR 6150 Page 193 1990, the word "descent" was deleted from the 1980 wording. In addition, the term "Mexican-Amer." used in 1980 was shortened further to "Mexican-Am." to reduce misreporting (of "American") in this category detected in the 1980 census. Finally, the 1990 question allowed those who reported as "other Spanish/ Hispanic" to write in their specific Hispanic origin group. Misreporting in the "Mexican-Amer." category of the 1980 census item on Spanish/Hispanic origin may affect the comparability of 1980 and 1990 census data for persons of Hispanic origin for certain areas of the country. An evaluation of the 1980 census item on Spanish/ Hispanic origin indicated that there was misreporting in the Mexican origin category by White and Black persons in certain areas. The study results showed evidence that the misreporting occurred in the South (excluding Texas), the Northeast (excluding the New York City area), and a few States in the Midwest Region. Also, results based on available data suggest that the impact of possible misreporting of Mexican origin in the 1980 census was severe in those portions of the above-mentioned regions where the Hispanic origin population was generally sparse. However, national 1980 census data on the Mexican origin population or total Hispanic origin population at the national level was not seriously affected by the reporting problem. (For a more detailed discussion of the evaluation of the 1980 census Spanish/Hispanic origin item, see the 1980 census Supplementary Reports.) The 1990 and 1980 census data on the Hispanic population are not directly comparable with 1970 Spanish origin data because of a number of factors: (1) overall improvements in the 1980 and 1990 censuses, (2) better coverage of the population, (3) improved question designs, and (4) an effective public relations campaign by the Census Bureau with the assistance of national and community ethnic groups. Specific changes in question design between the 1980 and 1970 censuses included the placement of the category "No, not Spanish/ Hispanic" as the first category in that question. (The corresponding category appeared last in the 1970 question.) Also, the 1970 category "Central or South American" was deleted because in 1970 some respondents misinterpreted the category; furthermore, the designations "Mexican-American" and "Chicano" were added to the Spanish/Hispanic origin question in 1980. In the 1970 census, the question on Spanish origin was asked of only a 5-percent sample of the population. HOUSEHOLD TYPE AND RELATIONSHIP Household A household includes all the persons who occupy a housing unit. A housing unit is a house, an apartment, a mobile home, a group of rooms, or a single room that is occupied (or if vacant, is intended 1 Page 194 ICPSR 6150 for occupancy) as separate living quarters. Separate living quarters are those in which the occupants live and eat separately from any other persons in the building and which have direct access from the outside of the building or through a common hall. The occupants may be a single family, one person living alone, two or more families living together, or any other group of related or unrelated persons who share living arrangements. In 100-percent tabulations, the count of households or householders always equals the count of occupied housing units. In sample tabulations, the numbers may differ as a result of the weighting process. Persons Per Household-A measure obtained by dividing the number of persons in households by the number of households (or householders). In cases where persons in households are cross-classified by race or Hispanic origin, persons in the household are classified by the race or Hispanic origin of the householder rather than the race or Hispanic origin of each individual. Relationship to Householder Householder-The data on relationship to householder were derived from answers to questionnaire item 2, which was asked of all persons in housing units. One person in each household is designated as the householder. In most cases, this is the person, or one of the persons, in whose name the home is owned, being bought, or rented and who is listed in column 1 of the census questionnaire. If there is no such person in the household, any adult household member 15 years old and over could be designated as the householder. Households are classified by type according to the sex of the householder and the presence of relatives. Two types of householders are distinguished: a family householder and a nonfamily householder. A family householder is a householder living with one or more persons related to him or her by birth, marriage, or adoption. The householder and all persons in the household related to him or her are family members. A nonfamily householder is a householder living alone or with nonrelatives only. Spouse-Includes a person married to and living with a householder. This category includes persons in formal marriages, as well as persons in common-law marriages. The number of spouses is equal to the number of "married-couple families" or "married-couple households" in 100-percent tabulations. The number of spouses, however, is generally less than half of the number of married persons with spouse present" in sample tabulations, since more than one married couple can live in a household, but only spouses of householders are specifically identified as "spouse." For sample tabulations, the number of "married persons with spouse 1 ICPSR 6150 Page 195 present" includes married-couple subfamilies and married couple families. Child-Includes a son or daughter by birth, a stepchild, or adopted child of the householder, regardless of the child's age or marital status. The category excludes sons-in-law, daughters-in-law, and foster children. Natural-Born or Adopted Son/Daughter-A son or daughter of the householder by birth, regardless of the age of the child. Also, this category includes sons or daughters of the householder by legal adoption, regardless of the age of the child. If the stepson/ step- daughter of the householder has been legally adopted by the householder, the child is still classified as a stepchild. Stepson/Stepdaughter-A son or daughter of the householder through marriage but not by birth, regard- less of the age of the child. If the stepson/ stepdaugh- ter of the householder has been legally adopted by the householder, the child is still classified as a stepchild. Own Child-never-married child under 18 years who is a son or daughter by birth, a stepchild, or an adopted child of the householder. In certain tabula- tions, own children are further classified as living with two parents or with one parent only. Own children of the householder living with two parents are by defi- nition found only in married-couple families. In a subfamily, an "own child" is a never-married child under 18 years of age who is a son, daughter, stepchild, or an adopted child of a mother in a mother-child subfamily, a father in a father-child subfamily, or either spouse in a married-couple sub- family. "Related children" in a family include own children and all other persons under 18 years of age in the household, regardless of marital status, who are related to the householder, except the spouse of the householder. Foster children are not included since they are not related to the householder. Other Relatives-in tabulations, includes any household member related to the householder by birth, marriage, or adoption, but not included specifically in another relationship category. In certain detailed tabulations, the following categories may be shown: Grandchild-The grandson or granddaughter of the 1 Page 196 ICPSR 6150 householder. Brother/Sister-The brother or sister of the house- holder, including stepbrothers, stepsisters, and broth- ers and sister's by adoption. Brothers-in-law and sisters-in-law are included in the "Other relative" category on the questionnaire. Parent-The father or mother of the householder, including a stepparent or adoptive parent. Fathers-in- law and mothers-in-law are included in the "Other relative" category on the questionnaire. Other Relatives-Anyone not listed in a reported category above who is related to the householder by birth, marriage, or adoption (brother-in-law, grandpar- ent, nephew, aunt, mother-in-law, daughter-in-law, cousin, and so forth). Nonrelatives-Includes any household member, including foster children not related to the householder by birth, marriage, or adoption. The following categories may be presented in more detailed tabulations: Roomer, Boarder, or Foster Child Roomer, boarder, lodger, and foster children or foster adults of the householder. Housemate or Roommate-A person who is not related to the householder and who shares living quarters primarily in order to share expenses. Unmarried Partner-A person who is not related to the householder, who shares living quarters, and who has a close personal relationship with the house- holder. Other Nonrelatives-A person who is not related by birth, marriage, or adoption to the householder and who is not described by the categories given above. When relationship is not reported for an individual, it is imputed according to the responses for age, sex, and marital status for that person while maintaining consistency with responses for other individuals in the house-hold. Unrelated Individual An unrelated individual is: (1) a householder living alone or with nonrelatives only, (2) a household member who is not related to the householder, or (3) a person living in group quarters who is not an inmate of an institution. 1 ICPSR 6150 Page 197 Family Type A family consists of a householder and one or more other persons living in the same household who are related to the householder by birth, marriage, or adoption. All persons in a household who are related to the householder are regarded as members of his or her family. A household can contain only one family for purposes of census tabulations. Not all households contain families since a household may comprise a group of unrelated persons or one person living alone. Families are classified by type as either a "married-couple family" or "other family" according to the sex of the householder and the presence of relatives. The data on family type are based on answers to questions on sex and relationship which were asked on a 100percent basis. Married-Couple Family-A family in which the house- holder and his or her spouse are enumerated as members of the same household. Other Family: Male Householder, No Wife Present-A family with a male householder and no spouse of householder present. Female Householder, No Husband Present-A fam- ily with a female householder and no spouse of householder present. Persons Per Family-A measure obtained by dividing the number of persons in families by the total number of families (or family householders). In cases where the measure, "persons in family" or "persons per family" are cross-tabulated by race or Hispanic origin, the race or Hispanic origin refers to the householder rather than the race or Hispanic origin of each individual. Subfamily A subfamily is a married couple (husband and wife enumerated as members of the same household) with or without never-married children under 18 years old, or one parent with one or more never-married children under 18 years old, living in a household and related to, but not including, either the householder or the householder's spouse. The number of subfamilies is not included in the count of families, since subfamily members are counted as part of the householder's family. Subfamilies are defined during processing of sample data. In selected tabulations, subfamilies are further classified by type: 1 Page 198 ICPSR 6150 married-couple subfamilies, with or without own children; mother-child subfamilies; and father-child subfamilies. Lone parents include people maintaining either one-parent families or one-parent subfamilies. Married couples include husbands and wives in both married-couple families and married-couple subfamilies. Unmarried-Partner Household An unmarried-partner household is a household other than a "married-couple household" that includes a householder and an "unmarried partner." An "unmarried partner" can be of the same sex or-of the opposite sex of the householder. An "unmarried partner" in an unmarried-partner household" is an adult who is unrelated to the householder, but shares living quarters and has a close personal relationship with the householder. Unmarried-Couple Household An unmarried-couple household is composed of two unrelated adults of the opposite sex (one of whom is the householder) who share a housing unit with or without the presence of children under 15 years old. Foster Children Foster children are nonrelatives of the householder and are included in the category, "Roomer, boarder, or foster child" on the questionnaire. Foster children are identified as persons under 18 years old and living in households that have no nonrelatives 18 years old and over (who might be parents of the nonrelatives under 18 years old. Stepfamily A stepfamily is a "married-couple family" with at least one stepchild of the householder present, where the householder is the husband. Comparability-The 1990 definition of a household is the same as that used in 1980. The 1980 relationship category "Son/daughter" has been replaced by two categories, "Natural-born or adopted son/daughter" and "Stepson/stepdaughter." "Grandchild" has been added as a separate category. The 1980 nonrelative categories: "Roomer, boarder' and "Partner, roommate" have been replaced by the categories "Roomer, boarder, or foster child ... .. Housemate, roommate," and "Unmarried partner." The 1980 nonrelative category "Paid employee" has been dropped. INCOME IN 1989 The data on income in 1989 were derived from answers to questionnaire items 32 and 33. Information on money income received in the calendar 1 ICPSR 6150 Page 199 year 1989 was requested from persons 15 years old and over. "Total income" is the algebraic sum of the amounts reported separately for wage or salary income; net nonfarm self-employment income; net farm self-employment income; interest, dividend, or net rental or royalty income; Social Security or railroad retirement income; public assistance or welfare income; retirement or disability income; and all other income. "Earnings" is defined as the algebraic sum of wage or salary income and net income from farm and nonfarm self -employment. "Earnings" represent the amount of income received regularly before deductions for personal income taxes, Social Security, bond purchases, union dues, medicare deductions, etc. Receipts from the following sources are not included as income: money received from the sale of property (unless the recipient was engaged in the business of selling such property); the value of income "in kind" from food stamps, public housing subsidies, medical care, employer contributions for persons, etc.; withdrawal of bank deposits; money borrowed; tax refunds; exchange of money between relatives living in the same household; gifts and lump-sum inheritances, insurance payments, and other types of lump-sum receipts. Income Type in 1989 The eight types of income reported in the census are defined as follows: 1. Wage or Salary Income-Includes total money earn- ings received for work performed as an employee during the calendar year 1989. It includes wages, salary, Armed Forces pay, commissions, tips, piece- rate payments, and cash bonuses earned before deductions were made for taxes, bonds, pensions, union dues, etc. 2. Nonfarm Self-Employment Income-Includes net money income (gross receipts minus expenses) from one's own business, professional enterprise, or partnership. Gross receipts include the value of all goods sold and services rendered. Expenses includes costs of goods purchased, rent, heat, light, power, depreciation charges, wages and salaries paid, business taxes (not personal income taxes), etc. 3. Farm Self-Employment Income--Includes net money income (gross receipts minus operating expenses) from the operation of a farm by a person on his or her own account, as an owner, renter, or sharecrop- per. Gross receipts include the value of all products sold, government farm programs, money received from the rental of farm equipment to others, and 1 Page 200 ICPSR 6150 incidental receipts from the sale of wood, sand, gravel, etc. Operating expenses include cost of feed, fertilizer, seed, and other farming supplies, cash wages paid to farmhands, depreciation charges, cash rent, interest on farm mortgages, farm building repairs, farm taxes (not State and Federal personal income taxes), etc. The value of fuel, food, or other farm products used for family living is not included as part of net income. 4. Interest, Dividend, or Net Rental Income-Includes interest on savings or bonds, dividends from stock- holdings or membership in associations, net income from rental of property to others and receipts from boarders or lodgers, net royalties, and periodic payments from an estate or trust fund. 5. Social Security Income-includes Social Security pensions and survivors benefits and permanent disability insurance payments made by the Social Security Administration priority to deductions for med- ical insurance, and railroad retirement insurance checks from the U.S. Government. Medicare reim- bursements are not included. 6. Public Assistance Income-Includes: (1) supplemen- tary security income payments made by Federal or State welfare agencies to low income persons who are aged (65 years old or over), blind, or disabled; (2) aid to families with dependent children, and (3) general assistance. Separate payments received for hospital or other medical care (vendor pay- ments) are excluded from this item. 7. Retirement or Disability Income-Includes: (1) retire- ment pensions and survivor benefits from a former employer, labor union, or Federal, State, county, or other governmental agency; (2) disability income from sources such as worker's compensation; com- panies or unions; Federal, State, or local govern- ment; and the U.S. military; (3) peridic receipts from annuities and insurance; and (4) regular income from IRA and KEOGH plans. 8. All Other Income-includes unemployment compen- sation, Veterans Administration (VA) payments, ali- mony and child support, contributions received peri- odically from persons not living in the household, military family allotments, net gambling winnings, and other kinds of periodic income other than earnings. 1 ICPSR 6150 Page 201 Income of Households-Includes the income of the householder and all other persons 15 years old and over in the household, whether related to the house-holder or not. Because many households consist of only one person, average household income is usually less than average family income. Income of Families and Persons-In compiling statistics on family income, the incomes of all members 15 years old and over in each family are summed and treated as a single amount. However, for persons 15 years old and over, the total amounts of their own incomes are used. Although the income statistics covered the calendar year 1989, the characteristics of persons and the composition of families refer to the time of enumeration (April 1990). Thus, the income of the family does not include amounts received by persons who were members of the family during all or part of the calendar year 1989 if these persons no longer resided with the family at the time of enumeration. Yet, family income amounts reported by related persons who did not reside with the family during 1989 but who were members of the family at the time of enumeration are included. However, the composition of most families was the same during 1989 as in April 1990. Median Income-The median divides the income distribution into two equal parts, one having incomes above the median and the other having incomes below the median. For households and families, the median income is based on the distribution of the total number of units including those with no income. The median for persons is based on persons with income. The median income values for all households, families, and persons are computed on the basis of more detailed income intervals than shown in most tabulations. Median household or family income figures of $50,000 or less are calculated using linear interpolation. For persons, corresponding median values of $40,000 or less are also computed using linear interpolation. All other median income amounts are derived through Pareto interpolation. (For more information on medians and interpolation, see the discussion under "Derived Measures.") Mean Income-This is the amount obtained by dividing the total income of a particular statistical universe by the number of units in that universe. Thus, mean household income is obtained by dividing total household income by the total number of households. For the various types of income the means are based on households having those types of income. "Per capita income" is the mean income computed for every man, woman, and child in a particular group. It is derived by dividing the total income of a particular group by the total population in that group. Care should be exercised in using and interpreting mean income values for small subgroups of the population. Because the mean is influenced strongly by extreme values in the distribution, it is especially 1 Page 202 ICPSR 6150 susceptible to the effects of sampling variability, misreporting, and processing errors. The median, which is not affected by extreme values, is, therefore, a better measure than the mean when the population base is small. The mean, nevertheless, is shown in some data products for most small subgroups because, when weighted according to the number of cases, the means can be added to obtained summary measures for areas and groups other than those shown in census tabulations. Limitation of the Data-Since questionnaire entries for income frequently are based on memory and not on records, many persons tended to forget minor or irregular sources of income and, therefore, underreport their income. Underreporting tends to be more pronounced for income sources that are not derived from earnings, such as Social Security, public assistance, or from interest, dividends, and net rental income. There are errors of reporting due to the misunderstanding of the income questions such as reporting gross rather than net dollar amounts for the two questions on net self-employment income, which resulted in an overstatement of these items. Another common error is the reporting of identical dollar amounts in two of the eight type of income items where a respondent with only one source of income assumed that the second amount should be entered to represent total income. Such instances of overreporting had an impact on the level of mean nonfarm or farm self-employment income and mean total income published for the various geographical subdivisions of the State. Extensive computer editing procedures were instituted in the data processing operation to reduce some of these reporting errors and to improve the accuracy of the income data. These procedures corrected various reporting deficiencies and improved the consistency of reported income items associated with work experience and information on occupation and class of worker. For example, if persons reported they were self-employed on their own farm, not incorporated, but had reported wage and salary earnings only, the latter amount was shifted to net farm self-employment income. Also, if any respondent reported total income only, the amount was generally assigned to one of the type of income items according to responses to the work experience and class-of-worker questions. Another type of problem involved nonreporting of income data. Where income information was not reported, procedures were devised to imputed appropriate values with either no income or positive or negative dollar amounts for the missing entries. In income tabulations for households and families, the lowest income group (e.g., less than $5,000) includes units that were classified as having no 1989 income. Many of these were living on income "in kind," savings, or gifts, were newly created families, or families in which the sole bread winner had recently died or left the household. However, many of the households and families who reported no income 1 ICPSR 6150 Page 203 probably had some money income which was not recorded in the census. The income data presented in the tabulations covers money income only. The fact that many farm families receive an important part of their income in the form of "free" housing and goods produced and consumed on the farm rather than in money should be taken into consideration in comparing the income of farm and nonfarm residents. Nonmoney income such as business expense accounts, use of business transportation and facilities, or partial compensation by business for medical and educational expenses was also received by some nonfarm residents. Many low income families also receive income "in kind" from public welfare programs. In comparing income data for 1989 with earlier years, it should be noted that an increase or decrease in money income does not necessarily represent a comparable change in real income, unless adjustments for changes in prices are made. Comparability-The income data collected in the 1980 and 1970 censuses are similar to the 1990 census data, but there are variations in the detail of the questions. In 1980, income information for 1979 was collected from persons in approximately 19 percent of all housing units and group quarters. Each person was required to report: * Wage or salary income * Net nonfarm self-employment income * Net farm self-employment income * Interest, dividend, or net rental or royalty income * Social Security income * Public assistance income * Income from all other sources Between the 1980 and 1990 censuses, there were minor differences in the processing of the data. In both censuses, all persons with missing values in one or more of the detailed type of income items and total income were designated as allocated. Each missing entry was imputed either as a "no" or as a dollar amount. If total income was reported and one or more of the type of income fields was not answered, then the entry in total income generally was assigned to one of the income types according to the socioeconomic char- acteristics of the income recipient. This person was designated as unallocated. In 1980 and 1990, all nonrespondents with income not reported (whether heads of households or other persons) were assigned the reported income of persons with similar characteristics. 1 Page 204 ICPSR 6150 There was a difference in the method of computer derivation of aggregate income from individual amounts between the two census processing operations. In the 1980 census, income amounts less than $100,000 were coded in tens of dollars, and amounts of $100,000 or more were coded in thousands of dollars; $5 was added to each amount coded in tens of dollars and $500 to each amount coded in thousands of dollars. Entries of $999,000 or more were treated as $999,500 and losses of $9,999 or more were treated as minus $9,999. In the 1990 census, income amounts less than $999,999 were keyed in dollars. Amounts of $999,999 or more were treated as $999,999 and losses of $9,999 or more were treated as minus $9,999 in all of the computer derivations of aggregate income. In 1970, information on income in 1969 was obtained from all members in every fifth housing unit and small group quarters (less than 15 persons) and every fifth person in all other group quarters. Each person was required to report: * Wage or salary income * Net nonfarm self-employment income * Net farm self-employment income * Social Security or Railroad Retirement * Public assistance or welfare payments * Income from all other sources If a person reported a dollar amount in wage or salary, net nonfarm self-employment income, or net farm self-employment income, the person was considered as unallocated only if no further dollar amounts were imputed for any additional missing entries. In 1960, data on income were obtained from all members in every fourth housing unit and from every fourth person 14 years old and over living in group quarters. Each person was required to report wage or salary income, net self-employment income, and income other than earnings received in 1959. An assumption was made in the editing process that no other type of income was received by a person who reported the receipt of either wage and salary income or self-employment but who had failed to report the receipt of other money income. For several reasons, the income data shown in census tabulations are not directly comparable with those that may be obtained from statistical summaries of income tax returns. Income, as defined for Federal tax purposes, differs somewhat from the Census Bureau concept. Moreover, the coverage of income tax statistics is different because of the exemptions of persons having small amounts of income 1 ICPSR 6150 Page 205 and the inclusion of net capital gains in tax returns. Furthermore, members of some families file separate returns and others file joint returns; consequently, the income reporting unit is not consistently either a family or a person. The earnings data shown in census tabulations are not directly comparable with earnings records of the Social Security Administration. The earnings record data for 1989 excluded the earnings of most civilian government employees, some employees of nonprofit organizations, workers covered by the Railroad Retirement Act, and persons not covered by the program because of insufficient earnings. Furthermore, earnings received from any one employer in excess of $48,000 in 1989 are not covered by earnings records. Finally, because census data are obtained from household questionnaires, they may differ from Social Security Administration earnings record data, which are based upon employers' reports and the Federal income tax returns of self-employed persons. The Bureau of Economic Analysis (BEA) of the Department of Commerce publishes annual data on aggregate and per-capita personal income received by the population for States, metropolitan areas, and selected counties. Aggregate income estimates based on the income statistics shown in census products usually would be less than those shown in the BEA income series for several reasons. The Census Bureau data are obtained directly from households, whereas the BEA income series is estimated largely on the basis of data from administrative records of business and governmental sources. Moreover, the definitions of income are different. The BEA income series includes some items not included in the income data shown in census publications, such as income "in kind," income received by nonprofit institutions, the value of services of banks and other financial intermediaries rendered to persons without the assessment of specific charges, Medicare payments, and the income of persons who died or emigrated prior to April 1, 1990. On the other hand the census income data include contributions for support received from persons not residing in the same household and employer contributions for social insurance. INDUSTRY, OCCUPATION, AND CLASS OF WORKER The data on industry, occupation, and class of worker were derived from answers to questionnaire items 28, 29, and 30 respectively. These questions were asked of a sample of persons. Information on industry relates to the kind of business conducted by a person's employing organization; occupation describes the kind of work the person does on the job. For employed persons, the data refer to the person's job during the reference week. For those who worked at two or more jobs, the data refer to the job at which the person worked the greatest number of hours. For unemployed persons, the data refer to their last job. The 1 Page 206 ICPSR 6150 industry and occupation statistics are derived from the detailed classification systems developed for the 1990 census as described below. The Classified Index of Industries and Occupations provided additional information on the industry and occupation classification systems. Respondents provided the data for the tabulations by writing on the questionnaires descriptions of their industry and occupation. These descriptions were keyed and passed through automated coding software which assigned a portion of the written entries to categories in the classification system. The automated system assigned codes to 59 percent of the industry enthes and 38 percent of the occupation entries. Those cases not coded by the computer were referred to clerical staff in the Census Bureau's Kansas City processing off ice for coding. The clerical staff converted the written questionnaire descriptions to codes by comparing these descriptions to entries in the Alphabetical Index of Industries and Occupations. For the industry code, these coders also referred to an Employer Name List (formerly called Company Name List). This list, prepared from the Standard Statistical Establishment List developed by the Census Bureau for the economic censuses and surveys, contained the names of business establishments and their Standard Industrial Classification (SIC) codes converted to population census equivalents. This list facilitated coding and maintained industrial classification comparability. Industry The industry classification system developed for the 1990 census consists of 235 categories for employed persons, classified into 13 major industry groups. Since 1940, the industrial classification has been based on the Standard Industrial Classification Manual (SIC). The 1990 census classification was developed from the 1987 SIC published by the Office of Management and Budget Executive Office of the President. The SIC was designed primarily to classify establishments by the type of industrial activity in which they were engaged. However, census data, which were collected from households, differ in detail and nature from those obtained from establishment surveys. Therefore, the census classification systems, while defined in SIC terms, cannot reflect the full detail in all categories. There are several levels of industrial classification found in census products. For example, the 1990 CP-2, Social and Economic Characteristics report includes 41 unique industrial categories, while the 1990 Summary Tape File 4 (STF 4) presents 72 categories. Occupation The occupational classification system developed for the 1990 census 1 ICPSR 6150 Page 207 consists of 500 specific occupational categories for employed persons arranged into 6 summary and 13 major occupational groups. This classification was developed to be consistent with the Standard Occupational Classification (SOC) Manual: 1980, published by the Off- ice of Federal Statistical Policy and Standards, U.S. Department of Commerce. Tabulations with occupation as the primary characteristic present several levels of occupational detail. The most detailed tabulations are shown in a special 1990 subject report and tape files on occupation. These products contain all 500 occupational categories plus industry or class of worker subgroupings of occupational categories. Some occupation groups are related closely to certain industries. Operators of transportation equipment, farm operators and workers, and private household workers account for major portions of their respective industries of transportation, agriculture, and private households. However, the industry categories include persons in other occupations. For example, persons employed in agriculture include truck drivers and bookkeepers; persons employed in the transportation industry include mechanics, freight handlers, and payroll clerks; and persons employed in the private household industry include occupations such as chauffeur, gardener, and secretary. Class of Worker The data on class of worker were derived from answers to questionnaire item 30. The information on class of worker refers to the same job as a respondent's industry and occupation and categorizes persons according to the type of ownership of the employing organization. The class of worker categories are defined as follows: Private Wage and Salary Workers-Includes persons who worked for wages, salary, commission, tips, pay-in-kind, or piece rates for a private for profit employer or a private not-for-profit, tax-exempt or charitable organization. Self-employed persons whose business was incorporated are included with private wage and salary workers because they are paid employees of their own companies. Some tabulations present data separately for these subcategories: "For profit," "Not for profit," and "Own business incorporated." Employees of foreign governments, the United Nations, or other formal international organizations were classified as "Private-not-for-profit." Government Workers-Includes persons who were employees of any local, State, or Federal governmental unit, regardless of the activity of the particular agency. For some tabulations, the data were presented separately for the three levels of government. Self-Employed Workers-Includes persons who worked for profit or fees in their own unincorporated business, profession, or trade, or who 1 Page 208 ICPSR 6150 operated a farm. Unpaid Family Workers-Includes persons who worked 15 hours or more without pay in a business or on a farm operated by a relative. Salaried/Self-Employed-in tabulations that categorize persons as either salaried or self-employed, the salaried category includes private and government wage and salary workers; self-employed includes self-employed persons and unpaid family workers. The industry category, "Public administration," is limited to regular government functions such as legislative, judicial, administrative, and regulatory activities of governments. Other government organizations such as schools, hospitals, liquor stores, and bus lines are classified by industry according to the activity in which they are engaged. On the other hand, the class of worker government categories include all government workers. Occasionally respondents supplied industry, occupation, or class of worker descriptions which were not sufficiently specific for precise classification or did not report on these items at all. Some of these cases were corrected through the field editing process and during the coding and tabulation operations. In the coding operation, certain types of incomplete entries were corrected using the Alphabetical Index of Industries and Occupations. For example, it was possible in certain situations to assign an industry code based on the occupation reported. Following the coding operations, there was a computer edit and an allocation process. The edit first determined whether a respondent was in the universe which required an industry and occupation code. The codes for the three items (industry, occupation, and class of worker) were checked to ensure they were valid and were edited for their relation to each other. Invalid and inconsistent codes were either blanked or changed to a consistent code. If one or more of the three codes were blank after the edit, a code was assigned from a "similar" person based on other items such as age, sex, education, farm or nonfarm residence, and weeks worked. If all the labor force and income data also were blank, all these economic items were assigned from one other person who provided all the necessary data. Comparability-Comparability of industry and occupation data was affected by a number of factors, primarily the systems used to classify the questionnaire responses. For both the industry and occupation classification systems, the basic structures were generally the same from 1940 to 1970, but changes in the individual categories limited comparability of the data from one census to another. These changes were needed to recognize the "birth" of new industries and occupations, the "death" of others, and the growth and 1 ICPSR 6150 Page 209 decline in existing industries and occupations, as well as, the desire of analysts and other users for more detail in the presentation of the data. Probably the greatest cause of incomparability is the movement of a segment of a category to a different category in the next census. Changes in the nature of jobs and respondent terminology, and refinement of category composition made these movements necessary. In the 1990 census, the industry classification had minor revisions to reflect recent changes to the SIC. The 1990 occupational classification system is essentially the same as that for the 1980 census. However, the conversion of the census classification to the SOC in 1980 meant that the 1990 classification system was less comparable to the classifications used prior to the 1980 census. Other factors that affected data comparability included the universe to which the data referred (in 1970, the age cutoff for labor force was changed from 14 years to 16 years); how the industry and occupation questions were worded on the questionnaire (for example, important changes were made in 1970); improvements in the coding procedures (the Employer Name List technique was introduced in 1960); and how the "not reported' cases are handled. Prior to 1970, they were placed in the residual categories, "Industry not reported" and "Occupation not reported." In 1970, an allocation process was introduced that assigned these cases to major groups. In 1990, as in 1980, the "Not reported" cases were assigned to individual categories. Therefore, the 1980 and 1990 data for individual categories included some numbers of persons who were tabulated in a "Not reported" category in previous censuses. The following publications contain information on the various factors affecting comparability and are particularly useful for understanding differences in the occupation and industry information from earlier censuses: U.S. Bureau of the Census, Changes Between the 1950 and 1960 Occupation and Industry Classifications With Detailed Adjustments of 1950 Data to the 1960 Classifications, Technical Paper No. 18, 1968; U.S. Bureau of the Census, 1970 Occupation and Industry Classification Systems in Terms of their 1960 Occupation and Industry Elements, Technical Paper No. 26, 1972; and U.S. Bureau of the Census, The Relationship Between the 1970 and 1980 Industry and Occupation Classification Systems, Technical Paper No. 59, 1988. For citations for earlier census years, see the 1980 Census of Population report, PC80-1 -D, Detailed Population Characteristics. The 1990 census introduced an additional class of worker category for "private not-for-profit" employers. This category is a subset of the 1980 category "employee of private employer" so there is no comparable data before 1990. Also in 1990, employees of foreign governments, the United Nations, etc., are classified as "private not-for-profit," rather than Federal Government as in 1970 and 1980. While in theory, there was a change in comparability, in practice, 1 Page 210 ICPSR 6150 the small number of U.S. residents working for foreign governments made this change negligible. Comparability between the statistics on industry and occupation from the 1990 census and statistics from other sources is affected by many of the factors described in the section on "Employment Status." These factors are primarily geographic differences between residence and place of work, different dates of reference, and differences in counts because of dual job holding. Industry data from population censuses cover all industries and all kinds of workers, whereas, data from establishments often excluded private household workers, government workers, and the self-employed Also, the replies from household respondents may have differed in detail and nature from those obtained from establishments. Occupation data from the census and data from government licensing agencies, professional associations, trade unions, etc., may not be as comparable as expected. Organizational listings often include persons not in the labor force or persons devoting all or most of their time to another occupation; or the same person may be included in two or more different listings. In addition, relatively few organizations, except for those requiring licensing, attained complete coverage of membership in a particular occupational field. JOURNEY TO WORK Place of Work The data on place of work were derived from answers to questionnaire item 22, which was asked of persons who indicated in question 21 that they worked at some time during the reference week. (For more information, see discussion under "Reference Week.") Data were tabulated for workers 16 years and over; that is, members of the Armed Forces and civilians who were at work during the reference week. Data on place of work refer to the geographic location at which workers carried out their occupational activities during the reference week. The exact address (number and street) of the place of work was asked, as well as the place (city, town, or post office); whether or not the place of work was inside or outside the limits of that city or town; and the county, State, and ZIP Code. If the person's employer operated in more than one location, the exact address of the location or branch where the respondent worked was requested. When the number and street name were unknown, a description of the location, such as the building name or nearest street or intersection, was to be entered. Persons who worked at more than one location during the reference week were asked to report the one at which they worked the greatest number of hours. Persons who regularly worked in several locations each day during the reference week were requested to give the address 1 ICPSR 6150 Page 211 at which they began work each day. For cases in which daily work did not begin at a central place each day, the person was asked to provide as much information as possible to describe the area in which he or she worked most during the reference week. In some tabulations, place-of-work locations may be defined as "in area of residence" and "outside area of residence." The area of residence may vary from table to table or even within a table, and refers to the particular area or areas shown. For example, in a table that provides data for counties, "in area of residence" refers to persons who worked in the same county in which they lived, while "outside area of residence" refers to persons whose workplace was located in a county different from the one in which they lived. Similarly, in a table that provides data for several types of areas, such as the State and its individual metropolitan areas (MA's), counties, and places, the place-of-work data will be vadable and is determined by the geographic level (State, MA, county, or place) shown in each section of the tabulation. In tabulations that present data for States, workplaces for the residents of the State may include, in addition to the State itself, each contiguous State. The category, "in noncontiguous State or abroad," includes persons who worked in a State that did not border their State of residence as well as persons who worked outside the United States. In tabulations that present data for an MSA/PMSA, place-of-work locations are specified to show the main destinations of workers living in the MSA/PMSA. (For more information on metropolitan areas (MA's), see Appendix A, Area Classifications.) All place-of-work locations are identified with respect to the boundaries of the MSA/PMSA as "inside MSA/PMSA" or "outside MSA/PMSA." Locations within the MSA/PMSA are further divided into each central city, and each county or county balance. Selected large incorporated places also may be specified as places of work. Within New England MSA/ PMSA'S, the places of work presented generally are cities and towns. Locations outside the MSA/PMSA are specified if they are important commuting destinations for residents of the MSA/ PMSA, and may include adjoining MSA/ PMSA's and their central cities, their component counties, large incorporated places, or counties, cities, or other geographic areas outside any MA. In tabulations for MSA/PMSA's in New England; Honolulu, Hawaii; and certain other MA's, some place-of-work locations are identified as "areas" (e.g., Area 1, Area 5, Area 12, etc.). Such areas consist of groups of towns, cities, census designated places (Honolulu MSA only), or counties that have been identified as unique place-of-work destinations. When an adjoining MSA/PMSA or MSA/PMSA remainder is specified as a place-of-work location, its components are not defined However, the components are presented in the 1990 CP-1, General Population Characteristics for Metropolitan Areas and the 1990 CH - 1 Page 212 ICPSR 6150 1, General Housing Characteristics for Metropolitan Areas reports. In tabulations that present data for census tracts outside MA's, place-of-work locations are defined as "in county of residence" and "outside county of residence." In areas where the workplace address was coded to the block level, persons were tabulated as working inside or outside a specific place based on the location of that address, regardless of the response to question 22c concerning city/town limits. In areas where it was impossible to code the workplace address to the block level, persons were tabulated as working in a place if a place name was reported in question 22b and the response to question 22c was either "Yes" or the item was left blank. In selected areas, census designated places (CDP's) may appear in the tabulations as places of work. The accuracy of place-of-work data for CDP's may be affected by the extent to which their census names were familiar to respondents, and by coding problems caused by similarities between the CDP name and the names of other geographic jurisdictions in the same vicinity. Place-of-work data are given for selected minor civil divisions (generally, cities, towns, and townships) in the nine Northeastern States, based on the responses to the place-of-work question. Many towns and townships are regarded locally as equivalent to a place and therefore, were reported as the place of work. When a respondent reported a locality or incorporated place that formed a part of a township or town, the coding and tabulating procedure was designed to include the response in the total for the township or town. The accuracy of the place-of-work data for minor civil divisions is greatest for the New England States. However, the data for some New England towns, for towns in New York, and for townships in New Jersey and Pennsylvania may be affected by coding problems that resulted from the unfamiliarity of the respondent with the minor civil division in which the workplace was located or when a township and a city or borough of the same or similar name are located close together. Place-of-work data may show a few workers who made unlikely daily work trips (e.g., workers who lived in New York and worked in California). This result is attributable to persons who worked during the reference week at a location that was different from their usual place of work, such as persons away from home on business. Comparability-The wording of the question on place of work was substantially the same in the 1990 census as it was in 1980. However, data on place of work from the 1990 census are based on the full census sample, while data from the 1980 census were based on only about one-half of the full sample. For the 1980 census, nonresponse or incomplete responses to the place-of-work question were not allocated, resulting in the use of "not reported" categories in the 1980 publications. However, for the 1 ICPSR 6150 Page 213 1990 census, when place of work was not reported or the response was incomplete, a work location was allocated to the person based on their means of transportation to work, travel time to work, industry, and location of residence and workplace of others. The 1990 publications, therefore, do not contain a "not reported" category for the place-of-work data. Comparisons between 1980 and 1990 census data on the gross number of workers in particular commuting flows, or the total number of persons working in an area, should be made with extreme caution. Any apparent increase in the magnitude of the gross numbers may be due solely to the fact that for 1990 the "not reported" cases have been distributed among specific place-of-work destinations, instead of tallied in a separate category as in 1980. Limitation of the Data-The data on place of work relate to a reference week; that is, the calendar week preceding the date on which the respondents completed their questionnaires or were interviewed by enumerators. This week is not the same for all respondents because the enumeration was not completed in 1 week. However, for the majority of persons, the reference week for the 1990 census is the last week in March 1990. The lack of a uniform reference week means that the place-of-work data reported in the census will not exactly match the distribution of workplace locations observed or measured during an actual workweek. The place-of-work data are estimates of persons 16 years old and over who were both employed and at work during the reference week (including persons in the Armed Forces). Persons who did not work during the reference week but had jobs or businesses from which they were temporarily absent due to illness, bad weather, industrial dispute, vacation, or other personal reasons are not included in the place-of-work data. Therefore, the data on place of work understate the total number of jobs or total employment in a geographic area during the reference week. It also should be noted that persons who had irregular, casual, or unstructured jobs during the reference week may have erroneously reported themselves as not working. The address where the individual worked most often during the reference week was recorded on the census questionnaire. If a worker held two jobs, only data about the primary job (the one worked the greatest number of hours during the preceding week) was requested. Persons who regularly worked in several locations during the reference week were requested to give the address at which they began work each day. For cases in which daily work was not begun at a central place each day, the person was asked to provide as much information as possible to describe the area in which he or she worked most during the reference week. Means of Transportation to Work 1 Page 214 ICPSR 6150 The data on means of transportation to work were derived from answers to questionnaire item 23a, which was asked of persons who indicated in question 21 that they worked at some time during the reference week. (For more information, see discussion under "Reference Week.") Means of transportation to work refers to the principal mode of travel or type of conveyance that the person usually used to get from home to work during the reference week. Persons who used different means of transportation on different days of the week were asked to specify the one they used most often, that is, the greatest number of days. Persons who used more than one means of transportation to get to work each day were asked to report the one used for the longest distance during the work trip. The category, "Car, truck, or van," includes workers using a car (including company cars but excluding taxicabs), a truck of one-ton capacity or less, or a van. The category, "Public transportation," includes workers who used a bus or trolley bus, streetcar or trolley car, subway or elevated, railroad, ferryboat, or taxicab even if each mode is not shown separately in the tabulation. The category, "Other means," includes workers who used a mode of travel which is not identified separately within the data distribution. The category, "Other means," may vary from table to table, depending on the amount of detail shown in a particular distribution. The means of transportation data for some areas may show workers using modes of public transportation that are not available in those areas (e.g, subway or elevated riders in an MA where there actually is no subway or elevated service). This result is largely due to persons who worked during the reference week at a location that was different from their usual place of work (such as persons away from home on business in an area where subway service was available) and persons who used more than one means of transportation each day but whose principal means was unavailable where they lived (for example, residents of nonmetropolitan areas who drove to the fringe of an MA and took the commuter railroad most of the distance to work). Private Vehicle Occupancy The data on private vehicle occupancy were derived from answers to questionnaire item 23b. This question was asked of persons who indicated in question 21 that they worked at some time during the reference week and who reported in question 23a that their means of transportation to work was "Car, truck, or van." (For more information, see discussion under "Reference Week.") Private vehicle occupancy refers to the number of persons who usually rode to work in the vehicle during the reference week. The category, "Drove alone," includes persons who usually drove alone to work as well as persons who were driven to work by someone who then drove back home or to a nonwork destination. The category, "Carpooled," includes workers who reported that two or more persons usually rode 1 ICPSR 6150 Page 215 to work in the vehicle during the reference week. Persons Per Car, Truck, or Van-This is obtained by dividing the number of persons who reported using a car, truck, or van to get to work by the number of such vehicles that they used. The number of vehicles used is derived by counting each person who drove alone as one vehicle, each person who reported being in a two-person carpool as one-half vehicle, each person who reported being in a three-person carpool as one-third vehicle, and so on, and then summing all the vehicles. Time Leaving Home to Go to Work The data on time leaving home to go to work were derived from answers to questionnaire item 24a. This question was asked of persons who indicated in question 21 that they worked at some time during the reference week and who reported in question 23a that they worked outside their home. The departure time refers to the time of day that the person usually left home to go to work during the reference week. (For more information, see discussion under "Reference Week.") Travel Time to Work The data on travel time to work were derived from answers to questionnaire item 24b. This question was asked of persons who indicated in question 21 that they worked at some time during the reference week and who reported in question 23a that they worked outside their home. Travel time to work refers to the total number of minutes that it usually took the person to get from home to work during the reference week. The elapsed time includes time spent waiting for public transportation, picking up passengers in carpools, and time spent in other activities related to getting to work. (For more information, see discussion under "Reference Week.") LANGUAGE SPOKEN AT HONE AND ABILITY TO SPEAK ENGLISH Language Spoken at Home Data on language spoken at home were derived from the answers to questionnaire items 15a and 15b, which were asked of a sample of persons born before April 1, 1985. Instructions mailed with the 1990 census questionnaire stated that a respondent should mark "Yes" in question 15a if the person sometimes or always spoke a language other than English at home and should not mark "Yes" if a language was spoken only at school or if speaking was limited to a few expressions or slang. For question 15b, respondents were instructed to print the name of the non-English language spoken at home. If the person spoke more than one language other than English, the person was to report the language spoken more often or the language learned first. The cover of the census questionnaire included information in Spanish 1 Page 216 ICPSR 6150 which provided a telephone number for respondents to call to request a census questionnaire and instructions in Spanish. Instruction guides were also available in 32 other languages to assist enumerators who encountered households or respondents who spoke no English. Questions 15a and 15b referred to languages spoken at home in an effort to measure the current use of languages other than English. Persons who knew languages other than English but did not use them at home or who only used them elsewhere were excluded Persons who reported speaking a language other than English at home may also speak English; however, the questions did not permit determination of the main or dominant language of persons who spoke both English and another language. (For more information, see discussion below on "Ability to Speak English.") For persons who indicated that they spoke a language other than English at home in question 15a, but failed to specify the name of the language in question 15b, the language was assigned based on the language of other speakers in the household; on the language of a person of the same Spanish origin or detailed race group living in the same or a nearby area; or on a person of the same ancestry or place of birth. In all cases where a person was assigned a non-English language, it was assumed that the language was spoken at home. Persons for whom the name of a language other than English was entered in question 15b, and for whom question 15a was blank were assumed to speak that language at home. The write-in responses listed in question 15b (specific language spoken) were transcribed onto computer files and coded into more than 380 detailed language categories using an automated coding system, The automated procedure compared write-in responses reported by respondents with entries in a computer dictionary, which initially contained approximately 2,000 language names. The dictionary was updated with a large number of new names, variations in spelling, and a small number of residual categories. Each write-in response was given a numeric code that was associated with one of the detailed categories in the dictionary. If the respondent listed more than one non-English language, only the first was coded. The write-in responses represented the names people used for languages they speak. They may not match the names or categories used by linguists. The sets of categories used are sometimes geographic and sometimes linguistic. Figure 1 provides an illustration of the content of the classification schemes used to present language data. For more information, write to the Chief, Population Division, U.S. Bureau of the Census, Washington, DC 20233. Household Language-in households where one or more persons (age 5 years old or over) speak a language other than English, the household language assigned to all household members is the non-English 1 ICPSR 6150 Page 217 language spoken by the first person with a non-English language in the following order: householder, spouse, parent, sibling, child, grandchild, other relative, stepchild unmarried partner, housemate or roommate, roomer, boarder, or foster child, or other nonrelative. Thus, persons who speak only English may have a nonEnglish household language assigned to them in tabulations of persons by household language. 1 Page 218 ICPSR 6150 Figure 1. Four-and Twenty-Five-Group Classifications of 1990 Census Languages Spoken at Home with Illustrative Examples Four-Group Twenty-Five-Group Classification Classification Examples Spanish Spanish Spanish, Ladino Other Indo- French French, Cajun, European Italian French Creole Portuguese German Yiddish Other West Afrikaans, Dutch, Germanic Pennsylvania Dutch Scandanavian Danish, Norwegian, Swedish Polish Russian South Slavic Serbocroatian, Bulgarian, Mace- donian, Slovene Other Slavic Czech, Slovak, Greek Ukrainian Indic Hindi, Bengali, Gujarathi, Punjabi, Romany, Sinhalese Other Indo- Armenian, Gaelic, European, not Lithuanian, Persian elsewhere classified Languages of Chinese Asia and the Japanese Pacific Mon-Khmer Cambodian Tagalog Korean Vietnamese Other languages Chamorro, Dravidian (part) languages, Hawaiian, Ilocano, Thai, Turkish All other lan- Arabic guages Hungarian Native North American languages Other languages Amharic, Syriac, (part) Finnish, Hebrew, languages of Central and South 1 ICPSR 6150 Page 219 America, Other languages of Africa 1 Page 220 ICPSR 6150 Ability to Speak English Persons 5 years old and over who reported that they spoke a language other than English in question 15a were also asked in question 15c to indicate their ability to speak English based on one of the following categories: "very well," Well,""Not well," or "Not at all." The data on ability to speak English represents the person's own perception about his or her own ability or, because census questionnaires are usually completed by one household member, the responses may represent the perception of another household member. The instruction guides and questionnaires that were mailed to households did not include any information on how to interpret the response categories in question 15c. Persons who reported that they spoke a language other than English at home but whose ability to speak English was not reported, were assigned the English-language ability of a randomly selected person of the same age, Spanish origin, nativity and year of entry, and language group. Linguistic isolation-A household in which no person age 14 years or over speaks only English and no person age 14 years or over who speaks a language other than English speaks English "Very well" is classified as "linguistically isolated." All the member's of a linguistically isolated household are tabulated as linguistically isolated, including members under age 14 years who may speak only English. Limitation of the Data-Persons who speak a language other than English at home may have first learned that language at school. However, these persons would be expected to indicate that they spoke English "Very well." Persons who speak a language other than English, but do not do so at home, should have been reported as not speaking a language other than English at home. The extreme detail in which language names were coded may give a false impression of the linguistic precision of these data. The names used by speakers of a language to identify it may reflect ethnic, geographic, or political affiliations and do not necessarily respect linguistic distinctions. The categories shown in the tabulations were chosen on a number of criteria, such as information about the number of speakers of each language that might be expected in a sample of the United States population. Comparability-Information on language has been collected in every census since 1890. The comparability of data among censuses is limited by changes in question wording, by the subpopulations to whom the question was addressed, and by the detail that was published. The same question on language was asked in the 1980 and 1990 censuses. This question on the current language spoken at home 1 ICPSR 6150 Page 221 replaced the questions asked in prior censuses on mother tongue; that is, the language other than English spoken in the person's home when he or she was a child; one's first language; or the language spoken before immigrating to the United States. The censuses of 1910-1940, 1960 and 1970 included questions on mother tongue. A change in coding procedure from 1980 to 1990 should have improved accuracy of coding and may affect the number of persons reported in some of the 380 plus categories. It should not greatly affect the 4-group or 25 group lists. In 1980, coding clerks supplied numeric codes for the written entries on each questionnaire using a 2,000 name reference list. In 1990 written entries were transcribed to a computer file and matched to a computer dictionary which began with the 2,000 name list, but expanded as unmatched names were referred to headquarters specialists for resolution. The question on ability to speak English was asked for the first time in 1980. In tabulations from 1980, the categories "Very well" and "Well" were combined. Data from other surveys suggested a major difference between the category "Very well" and the remaining categories. In tabulations showing ability to speak English, persons who reported that they spoke English "Very well" are presented separately from persons who reported their ability to speak English as less than "Very well." MARITAL STATUS The data on marital status were derived from answers to questionnaire item 6, which was asked of all persons. The marital status classification refers to the status at the time of enumeration. Data on marital status are tabulated only for persons 15 years old and over. All persons were asked whether they were "now married," "widowed," "divorced," "separated," or "never married." Couples who live together (unmarried persons, persons in common-law marriages) were allowed to report the marital status they considered the most appropriate. Never Married-Includes all persons who have never been married, including persons whose only marriage(s) was annulled. Ever Married-Includes persons married at the time of enumeration (including those separated, widowed, or divorced. Now Married, Except Separated-Includes persons whose current marriage has not ended through widowhood, divorce, or separation (regardless of previous marital history). The category may also include couples who live together or persons in common-law marriages if they consider this category the most appropriate. In certain tabulations, currently married persons are further classified as "spouse present" or "spouse absent." 1 Page 222 ICPSR 6150 Separated-Includes persons legally separated or otherwise absent from their spouse because of marital discord. Included are persons who have been deserted or who have parted because they no longer want to live together but who have not obtained a divorce. Widowed-Includes widows and widowers who have not remarried. Divorced-Includes persons who are legally divorced and who have not remarried. In selected sample tabulations, data for married and separated persons are reorganized and combined with information on the presence of the spouse in the same household. Now Married-All persons whose current marriage has not ended by widowhood or divorce. This category includes persons defined above as "separated." Spouse Present-Married persons whose wife or husband was enumerated as a member of the same household, including those whose spouse may have been temporarily absent for such reasons as travel or hospitalization. Spouse Absent-Married persons whose wife or husband was not enumerated as a member of the same household. This category also includes all married persons living in group quarters. Separated-Defined above. Spouse Absent, Other-Married persons whose wife or husband was not enumerated as a member of the same household, excluding separated, Included is any person whose spouse was employed and living away from home or in an institution or absent in the Armed Forces. Differences between the number of currently married males and the number of currently married females occur because of reporting differences and because some husbands and wives have their usual residence in different areas. In sample tabulations, these differences can also occur because different weights are applied to the individual's data. Any differences between the number of "now married, spouse present" males and females are due solely to sample weighting. By definition, the number's would be the same. When marital status was not reported, it was imputed according to the relationship to the householder and sex and age of the person. Comparability-The 1990 marital status definitions are the same as those used in 1980 with the exception of the term "never married" 1 ICPSR 6150 Page 223 which replaces the term 1. single" in tabulations. A general marital status question has been asked in every census since 1880. MOBILITY LIMITATION STATUS The data on mobility limitation status were derived from answers to questionnaire item 19a, which was asked of a sample of persons 15 years old and over. Persons were identified as having a mobility limitation if they had a health condition that had lasted for 6 or more months and which made it difficult to go outside the home alone. Examples of outside activities on the questionnaire included shopping and visiting the doctor's office. The term "health condition" referred to both physical and mental conditions. A temporary health problem, such as a broken bone that was expected to heal normally, was not considered a health condition. Comparability-This was the first time that a question on mobility limitation was included in the census. PLACE OF BIRTH The data on place of birth were derived from answers to questionnaire item 8, which was asked on a sample basis. The place-of-birth question asked respondents to report the U.S. State, commonwealth or territory, or the foreign country where they were born. Persons born outside the United States were asked to report their place of birth according to current international boundaries. Since numerous changes in boundaries of foreign countries have occurred in the last century, some persons may have reported their place of birth in terms of boundaries that existed at the time of their birth or emigration, or in accordance with their own national preference. Persons not reporting place of birth were assigned the birthplace of another family member or were allocated the response of another person with similar characteristics. Persons allocated as foreign born were not assigned a specific country of birth but were classified as "Born abroad, country not specified." Nativity-information on place of birth and citizenship were used to classify the population into two major categories: native and foreign born. When information on place of birth was not reported, nativity was assigned on the basis of answers to citizenship, if reported, and other characteristics. Native-Includes persons born in the United States, Puerto Rico, or an outlying area of the United States. The small number of persons who were born in a foreign country but have at least one American parent also are included in this category. 1 Page 224 ICPSR 6150 The native population is classifi