National Survey on Drug Use and Health, 2002 (ICPSR 3903)

1. Data were collected and prepared for release by Research Triangle Institute, Research Triangle Park, NC.

2. Prior to the 2002 survey, this series was titled National Household Surveys on Drug Abuse.

3. Although the design of the 2002 survey is similar to the design of the 1999 through 2001 surveys, there are important methodological differences that affect the 2002 estimates. Each NSDUH respondent in 2002 was given an incentive payment of $30. This change resulted in an improvement in the survey response rate. In addition, new population data from the 2000 decennial Census became available for use in NSDUH sample weighting procedures. Therefore the data from 2002 and later should not be compared with data collected in 2001 or earlier to assess changes over time.

4. For selected variables, statistical imputation was performed following logical inference to replace missing responses. These variables are identified in the codebook as "...LOGICALLY ASSIGNED" for the logical procedure, or by the designation "IMPUTATION-REVISED" in the variable label when the statistical procedure was also performed. The names of statistically imputed variables begin with the letters "IR". For each imputation-revised variable there is a corresponding imputation indicator variable that indicates whether a case's value on the variable resulted from an interview response or was imputed. Missing values for some demographic variables were imputed by the unweighted hot-deck technique used in previous surveys. Beginning in 1999, imputation of missing values for most variables was accomplished using predictive mean neighborhoods (PMN), a new procedure developed specifically for this survey. Both the hot-deck and PMN imputation procedures are described in the codebook.

5. To protect the privacy of respondents, all variables that could be used to identify individuals have been encrypted or collapsed in the public use file. To further ensure respondent confidentiality, the data producer used data substitution and deletion of state identifiers and a subsample of records in the creation of the public use file.

6. Previously published estimates may not be exactly reproducible from the variables in the public use file due to the disclosure protection procedures that were implemented.

7. The setup and dictionary files for Stata are designed to be compatible with StataSE, Version 8. This is a large data file requiring that approximately 250 megabytes of Random Access Memory be allocated to Stata. Operations within Stata, including conversion of the ASCII data to Stata format, are likely to be slow. Analysts may wish to download subsets of data from the SAMHDA Data Analysis System (DAS) for use with Stata.

8. Since 1999, the survey sample has employed a 50-State design with an independent, multistage area probability sample for each of the 50 States and the District of Columbia.

• United States Department of Health and Human Services. Substance Abuse and Mental Health Services Administration. Office of Applied Studies. National Survey on Drug Use and Health, 2002. ICPSR03903-v6. Ann Arbor, MI: Inter-university Consortium for Political and Social Research [distributor], 2015-11-23. http://doi.org/10.3886/ICPSR03903.v6

2015-11-23 Covers for the PDF documentation were revised.

2013-06-24 Released Methodological Resources documentation and updated xml file to include variable groupings.

2013-03-07 The 2002 NSDUH public-use data file has been updated to include 17 new variables related to respondent drug use, mental health treatment, and geography. Please view Table 4 of the codebook for more information on these variables.

2006-10-26 The data producer resupplied the data file and codebook documentation. Thirty-three variables were modified, 20 variables were dropped, and 118 new variables were added. Some of these changes were to correct for data errors, but most of these changes were done to provide consistency with the 2004 NSDUH study. Of these changes, the most important change to note is that two study design variables (VEREP and VESTR) were revised to provide consistency with the 2004 study, which collapsed the strata in order to maximize the number of people in each replicate.

2004-02-24 Variable NRCH17_2 (RECODED # R's CHILDREN under 18 IN HOUSEHOLD) was replaced to correct a coding error.

2004-02-05 ICPSR data undergo a confidentiality review and are altered when necessary to limit the risk of disclosure. ICPSR also routinely creates ready-to-go data files along with setups in the major statistical software formats as well as standard codebooks to accompany the data. In addition to these procedures, ICPSR performed the following processing steps for this data collection:

• Performed consistency checks.
• Created online analysis version with question text.
• Checked for undocumented or out-of-range codes.