Sample Design and Data Collection

Each month, the U.S. Census Bureau selects respondents for the NCVS using a rotating paneldesign. Households are selected into the sample using a stratified, multistage cluster design. In the first stage, the primary sampling units (PSUs), consisting of counties or groups of counties, are selected, and smaller areas, called Enumeration Districts (ED), are selected within each sampled PSU. Within each ED, clusters of four households, called segments, are selected. Acrossall EDs, sampled households are then divided into discrete groups (rotations), and all age-eligible individuals in the households become part of the panel.

Once in the panel, respondents are administered the NCVS every 6 months (for a total of seven interviews over a 3-year period) to determine whether they have been victimized during the 6 months preceding the interview. The SCS questionnaire is administered after the NCVS to eligible persons ages 12 through 18 in the sample. The first interview is considered the incoming rotation, while the second through the seventh interviews are considered continuing rotations.

The first NCVS/SCS interview is administered face-to-face using computer-assisted personal interviewing (CAPI); the remaining interviews are administered by telephone using CAPI unless circumstances call for an in-person interview. After the seventh interview, the household leaves the panel and a new household is rotated into the sample. This type of rotation scheme is used to reduce the respondent burden that might result if households were to remain in the sample permanently. It should be noted that the data from the NCVS/SCS interviews obtained in the incoming rotation are included in the SCS data file. The implications of examining data from unbounded and bounded interviews are discussed in the Survey Limitations section below.

The SCS is administered to all eligible NCVS respondents ages 12 through 18 within NCVS households between January and June of the year of data collection. In 2009, there were approximately 61,000 households in the NCVS sample, and 8,986 NCVS household members were between ages 12 and 18. In order to complete the SCS, respondents must have completed the NCVS and meet certain criteria specified in a set of screening questions in the SCS questionnaire. These criteria require students to be in grades 6–12, to be currently enrolled in a primary or secondary education program leading to a high school diploma or enrolled sometime during the school year of the interview, and not to have been exclusively homeschooled during the school year.¹ In 2009, some 5,023 respondents completed the 2009 SCS and 4,326 met the criteria for inclusion in this analysis. These criteria are detailed in the glossary of variables, found later in this appendix.

The prevalence of victimization in the 2009 SCS was calculated by using NCVS incident variables appended to the SCS data file. The NCVS "type of crime" (TOC) variable was used to classify victimizations of students in the SCS as serious violent, violent, or theft. NCVS-2 variables asking where the incident happened and what the victim was doing when it happened were used to ascertain whether the incident happened at school.

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¹ Persons who have dropped out of school, have been expelled or suspended from school, or are temporarily absent from school for any other reason, such as illness or vacation, can complete the SCS as long as they have attended school at any time during the school year of the interview. Students who receive all of their education through homeschooling are not included past the screening questions, and those who receive part of their education through homeschooling are not included in this report.