School Survey on Crime and Safety (SSOCS), 2004 (ICPSR 25681)

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Study Purpose View help for Study Purpose

The SSOCS is the primary source of school-level data on crime and safety for the United States Department of Education. It provides nationwide estimates of crime, discipline, disorder, programs, and policies in public schools. Data on crime, violence, and disorder in the nation's schools are collected to provide policymakers, parents, and educators with the information necessary to identify emerging problems and to gauge the safety of American schools.

Study Design View help for Study Design

SSOCS:2004 was conducted as a mail survey with telephone follow-up. Six months before the onset of data collection, NCES began working with the school districts of sample schools that required prior approval to participate in the survey. In late February 2004, advance letters were sent to school administrators of sample schools that included the date of the first questionnaire mailing and a toll-free number to call with any questions. Approximately one week later, SSOCS questionnaires were mailed to administrators with a cover letter describing the importance of the survey and a brochure providing additional information about it. On the same day the questionnaires were mailed to schools, letters were sent to sample district superintendents and the Chief State School Officer of each state to inform them that schools within their districts and states, respectively, had been selected to participate in SSOCS:2004. The letters included information about the survey and were accompanied by a copy of the questionnaire and brochure that were sent to schools. The letter was not designed to ask for permission from these officials to participate in the survey but rather, it was designed by NCES as a vehicle to enhance participation. Starting approximately one week after the first questionnaire mailing, follow-up telephone prompts were used to verify that the questionnaire was received and to encourage survey response. As an alternative to replying by mail, data were also accepted by fax submission and over the telephone. Data collection ended on June 4, 2004. Returned questionnaires were examined for quality and completeness using both manual and computerized edits. Out of 227 items on the questionnaire, 101 were identified as key (critical) items. If the survey had more than 40 percent of all items missing or more than 20 percent of critical items missing, the respondent was recontacted to resolve issues related to the missing data. In cases where the recontacts failed to produce a satisfactory resolution, imputation was used to resolve data quality issues for questionnaires that had at least 60 percent of all items and 80 percent of critical items completed. Schools whose questionnaires did not meet the 60/80 criterion and for which recontact was not successful were reclassified as nonrespondents.

Sample View help for Sample

The sampling frame for SSOCS:2004 was constructed from the public school universe file created for the 2003-2004 Schools and Staffing Survey (SASS). The SASS frame was derived from the 2001-2002 NCES Common Core of Data (CCD) Public School Universe file. The CCD is an annual national database of all public K-12 schools and school districts. Certain types of schools are excluded from the CCD Public School Universe File in order to meet the sampling needs of SASS, including those in the outlying United States territories, overseas Department of Defense schools, newly closed schools, home schools, and schools with high grades of kindergarten or lower. Additional schools are then excluded from the SASS frame to meet the sampling needs of SSOCS, including local education agencies that appear to be schools and "intermediate units" in California and Pennsylvania. Further information on sampling can be found in the School Survey on Crime and Safety: 2003-2004 Data File User's Manual.

Universe View help for Universe

Public elementary and secondary schools in the United States.

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Response Rates View help for Response Rates

Unweighted response rate: 74.7 percent, Weighted response rate: 77.2 percent

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2010-03-04

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Sample weights allow inferences to be made about the population from which the sample units were drawn. Because of the complex nature of the SSOCS:2004 sample design, these weights are necessary to obtain population-based estimates, to minimize bias arising from differences between responding and nonresponding schools, and to calibrate the data to known population characteristics in a way that reduces sampling error. The procedures used to create the SSOCS sampling weights are described below. An initial (base) weight was first determined within each stratum by calculating the ratio of the number of schools available in the sampling frame to the number of schools selected. Because some schools refused to participate, the responding schools did not necessarily constitute a random sample from the schools in the stratum. In order to reduce the potential of bias from nonresponse, weighting classes were determined by using a statistical algorithm similar to CHAID (i.e., chi-square automatic interaction detector) to partition the sample such that schools within a weighting class were homogenous with respect to their probability of responding. The predictor variables for the analysis were instructional level, region, enrollment size, percent minority, student-to-teacher ratio, percentage of students eligible for free or reduced-price lunch, and number of full-time-equivalent teachers. When the number of responding schools in a class was sufficiently small, the weighting class was combined with another to avoid the possibility of large weights. After combining the necessary classes, the base weights were adjusted by dividing the base weight by the response rate in each class, so that the weighted distribution of the responding schools resembled the initial distribution of the total sample. The non-response-adjusted weights were then poststratified to calibrate the sample to known population totals. For SSOCS:2004, two dimension margins were set up for the poststratification: (1) instructional level and school enrollment size, and (2) instructional level and locale. An iterative process known as the raking ratio adjustment brought the weights into agreement with the known control totals. Poststratification works well when the population not covered by the survey is similar to the covered population within each poststratum. Thus, to be effective, the variables that define the poststrata must be correlated with the variables of interest, they must be well measured in the survey, and control totals must be available for the population as a whole. Similar to SSOCS:2000 (ICPSR 3964), all three requirements were satisfied by the aforementioned poststratification margins.