2025 SCS OMB Supporting Statement B_final

School Crime Supplement to the National Crime Victimization Survey

OMB Control Number 1121-0184

OMB Expiration Date: 11/30/2024

B. COLLECTION OF INFORMATION EMPLOYING STATISTICAL METHODS

1. Universe and Respondent Selection

The universe for the National Crime Victimization Survey (NCVS) national sample is all persons age 12 or older in the more than 120 million U.S. households and persons 12 or older living in non-institutional group quarters (GQ) (except crews of vessels, military in barracks, and those at domestic violence shelters or living quarters for victims of natural disasters). In 2025, the annual NCVS national sample is planned to be approximately 260,000 designated addresses located in 542 stratified Primary Sampling Units (PSUs) throughout the U.S. From January through June 2025, when the 2025 NCVS School Crime Supplement (SCS) is in the field, the NCVS national sample will include about 130,000 designated addresses.

The sample universe for the SCS is all persons ages 12 to 18 living in NCVS interviewed households who have attended public or private school during the current school year (grades 6 through 12).¹ Students are eligible for the SCS if they were homeschooled for part of the school year and attended a public or private school during the other part of the school year, or attended a homeschool cooperative in person.² Students who were homeschooled the entire school year are ineligible for the SCS.

Master Address File. The Master Address File (MAF) contains all addresses from the most recent decennial census plus updates from the U.S. Postal Service, state and local address lists, and other address listing operations. The MAF is the frame for the target NCVS population. Every ten years, the Census Bureau redesigns the samples for all of their continuing demographic surveys, including the NCVS. In general, the purpose of these redesigns is to capture population shifts measured by the most recent decennial census. In 2015, the 2000 sample design started to phase out and the 2010 sample design started to be phased in. As part of the 2010-based sample design, new addresses are selected each year from the MAF based upon the 2010 Decennial Census of Population and Housing and addresses from the U.S. Postal Service. New housing units are added to the MAF, and therefore the NCVS sampling frame, through semiannual updates.

Sample Selection

The sample design for the NCVS is a stratified, multi-stage cluster sample. Sample selection for the NCVS is done in three stages: the selection of PSUs, the selection of sample hits within sampled PSUs, and the selection of all eligible persons and households within the sample hits.³ Sample hits are clusters of four typically nearby housing units, but they can also be four housing unit equivalents within one or more group quarters.

Stage 1. Defining and Selecting PSUs

Defining PSUs – PSUs are defined, stratified, and selected once every ten years. Formation of PSUs begins with listing counties, independent cities, and other county equivalents in the target area. For the NCVS, the target area is all 50 states and the District of Columbia. The PSUs comprising the first stage of the sample are formed from counties or groups of adjacent counties based upon data from the most recent decennial census and the American Community Survey (ACS). The counties are either PSUs by themselves or grouped with one or more contiguous counties to form PSUs. For counties that are grouped, the groupings are based on certain characteristics such as state boundaries, total land area, current and projected population counts, metropolitan area status, and potential natural barriers such as rivers and mountains. The resulting county groupings are called PSUs.

After the PSUs are formed, the large PSUs and those within large metropolitan areas (specifically, Core Based Statistical Areas (CBSAs)) are designated self-representing (SR). The remaining smaller PSUs are designated non-self-representing (NSR). Determining which PSUs are considered small and which are considered large depends on the survey’s SR population cutoff (generally 100,000) and whether estimates are desired for the state. In the 2010 design, all PSUs in the top 85 CBSAs were designated as SR. In the 22 states for which NCVS made state-level estimates, additional PSUs were designated as SR based on a formula to achieve targeted coefficients of variation. Other than the top 85 CBSAs, there is no general rule to differentiate between SR and NSR PSUs.

Stratifying PSUs – For the 2010-based sample design, each SR PSU formed its own stratum. The NSR PSUs were grouped with similar NSR PSUs within states to form strata. For the NCVS, decennial census counts, ACS estimates, and administrative crime data drawn from the FBI’s Uniform Crime Reporting (UCR) Program are used to stratify the NSR PSUs to form strata as similar or homogeneous as possible. Just as the SR PSUs must be large enough to support a full workload, so must each NSR stratum. The most efficient stratification scheme was determined by minimizing the between-PSU variance within stratum and maximizing the between-stratum variance.

Selecting PSUs –In general, the SR PSUs are automatically included in the sample or selected with certainty. NSR PSUs are sampled with probability proportional to the population size. The NSR PSUs in the 2010-based sample were selected with Ohlsson’s (2000)⁴ method of maximizing the sample overlap, independently of the 2000-based sample. This method will provide a basis for maximizing the overlap between the 2010- and 2020-based samples. One PSU was selected from each NSR stratum. The 2010-based sample design NCVS sample includes 339 SR PSUs and 203 NSR PSUs (out of 1,648 NSR PSUs).

Stage 2. Preparing Frames and Sampling within PSUs

Frame Determination – The 2010-based sample design selects its sample from two dynamic address-based sampling frames, one for housing units (HUs) and one for group quarters (GQs). Both frames are based upon the MAF, which is a national inventory of addresses. The MAF is continually updated by various Census Bureau programs and external sources. New housing units are added to the MAF, and therefore the NCVS sampling frame, through semiannual updates from a variety of address sources, including the U.S. Postal Service Delivery Sequence File, local government files, and field listing operations.

In the 2010-based sample design, each address in the country was assigned to the housing unit or GQ frame based on the type of living quarters. Two types of living quarters are defined in the decennial census. The first type is an HU. An HU is a group of rooms or a single room occupied as separate living quarters or intended for occupancy as separate living quarters. An HU may be occupied by a family or one person, as well as by two or more unrelated persons who share the living quarters. The second type of living quarters is GQ. GQs are living quarters where residents share common facilities or receive formally authorized care. About 3% of the population counted in the 2010 Census resided in GQs. Of those, less than half resided in non-institutionalized GQs.

Within-PSU Sampling – All of the Census Bureau’s continuing demographic surveys, such as the NCVS, are sampled together. This procedure takes advantage of updates from the January MAF delivery and ACS data. This within-PSU selection occurs every year for housing units and every three years for GQs.

Selection of samples is done one survey at a time (sequentially). Each survey determines how the unit addresses within the frame should be sorted prior to sampling. For the NCVS, each frame is sorted by geographic variables. A systematic sampling procedure is used to select addresses from each frame. A skeleton sample is also selected in every PSU. Every six months new addresses on the MAF are matched to the skeleton frame. The skeleton frame allows the sample to be refreshed with new addresses and thereby reduces the risk of undercoverage errors due to an outdated frame.

Addresses selected for a survey are removed from the frames, leaving an unbiased or clean universe behind for the next survey that is subsequently sampled. By leaving a clean universe for the next survey, duplication of addresses across surveys is avoided. This is done to help preserve response rates by ensuring that no unit falls into more than one survey sample.

Stage 3. Persons within Sample Addresses

The last stage of sampling is done during the initial contact of the sample address during the data collection phase. For the NCVS, if the address is a residence and the occupants agree to participate, then an attempt is made to interview every person age 12 or older who lives at the address. The NCVS has procedures to determine who lives in the sample unit and a household roster is completed with names and other demographic information of all persons who live there. If someone moves out (in) of the household during the interviewing cycle, he or she is removed from (added to) the roster. For the SCS, if the address is a residence and the occupants agree to participate, then an attempt is made to interview every person ages 12 to 18 who lives at the resident address and completes the NCVS Crime Screener instrument (NCVS-1).

The expected NCVS sample size for January through June 2025 is 130,000 households. Per month, approximately 2,022 persons, ages 12 to 18, in these households will be eligible to be interviewed for the supplement during the SCS administration for a total of 12,129 possible interviews. Generally, interviewers are able to obtain SCS interviews with approximately 45.6% of the SCS eligible household members in occupied units in sample in any given month. A total of 5,530 persons ages 12 to 18 are expected to be interviewed for the SCS during the 6-month collection period.

State Samples

Beginning in January 2016, BJS and the Census Bureau increased and reallocated the existing national sample in the 22 largest states. The states receiving a sample boost include Arizona, California, Colorado, Florida, Georgia, Illinois, Indiana, Maryland, Massachusetts, Michigan, Minnesota, Missouri, New Jersey, New York, North Carolina, Ohio, Pennsylvania, Tennessee, Texas, Virginia, Washington, and Wisconsin. In 2019, each of these 22 states had a population greater than 5 million persons and in total, these 22 states comprised 79% of the U.S. population.⁵ In each of the 22 states, enough sample was selected with the goal of achieving a 10% relative standard error (RSE) for a three-year average violent victimization rate of 0.02. The state estimates for 2017-2019 fall somewhat short of this precision goal while still measuring important differences among this group of states.⁶

The underlying assumption of the subnational sample design is that three years of data will be needed to produce precise estimates of violent crime, which is experienced by about 1% of the population. Sample sizes in the remaining 28 states and the District of Columbia were determined to ensure full representation and unbiased estimates at the national level. Unlike the 2000 sample design, in the 2010-based sample design, no strata cross state boundaries and all 50 states and the District of Columbia have at least one sampled PSU.

Rotating Panel Design

The NCVS uses a rotating panel design. The sample consists of seven groups for each month of enumeration. Each of these groups stays in the sample for an initial interview and six subsequent interviews, for a total of seven interviews for the typical household. During the course of the 6-month period when the SCS is administered, a full sample of seven rotation groups will be interviewed (one-sixth each month). One rotation group enters the sample for its first interview each month.

Weighting and Estimation

The purpose of the SCS is to make inferences about school-related victimizations for the population of students ages 12 to 18 in the U.S. Before such inferences can be drawn, it is necessary to adjust, or weight, the sample of people to ensure it is similar to the entire population in this age group. The SCS weights are a combination of household-level and person-level adjustment factors. Household and person respondents from the NCVS sample are adjusted on a bi-annual basis to represent the U.S. population age 12 or older. For the SCS, the population is restricted to students ages 12 to 18 who attend public school, private school, or a homeschool cooperative in person during the current school year.

NCVS household and person weights are first adjusted to account for any subsampling that occurs within large GQs. The NCVS nonresponse weighting adjustment then allocates the sampling weights of nonresponding households and persons to respondents with similar characteristics. Additional factors are then applied to correct for the differences between the sample distributions of age, race, Hispanic origin, and sex and the population distributions of these characteristics. The resulting weights are assigned to all interviewed households and persons in the NCVS file.

SCS weighting begins with the NCVS final person weight, which is then multiplied by an SCS noninterview adjustment factor. SCS noninterview adjustment factors are computed by distributing the weights of SCS noninterviews to the weights of the SCS interviews, with adjustment cells determined by age, race, Hispanic origin, and sex. The result is an SCS person-level weight that can be used for producing estimates from the SCS variables.

Variance Estimates

The NCVS and SCS estimates come from a sample, so they may differ from figures from an enumeration of the entire population using the same questionnaires, instructions, and enumerators. For a given estimator, the average squared difference between estimates based on repeated samples and the estimate that would result if the sample were to include the entire population is known as sampling error.⁷ The sampling error quantifies the amount of uncertainty in an estimate as a result of selecting a sample.

Variance estimates can be derived using direct estimation or generalized variance functions (GVFs). Replication methods provide estimates of variance for a wide variety of designs using probability sampling, even when complex estimation procedures are used. This method requires the sample selection, data collection, and estimation procedures to be carried out (i.e., replicated) several times. Dispersing the resulting estimates can be used to measure the variance of the full sample.

In addition, the Census Bureau produces parameters for GVFs that estimate the variance of any crime count estimate based on the value of the estimate.⁸ To do this, estimates and their relative variances are fit to a regression model using an iterative weighted least squares procedure where the weight is the inverse of the square of the predicted relative variance. GVFs are not the only means by which to estimate variance in the NCVS. Direct estimation of variance is possible as well with instructions available on the BJS website. BJS maintains an active research program on direct variance and GVF estimation methods that seeks to improve the quality and accuracy of NCVS estimates and make technical information available to data users to support research.

2. Procedures for Collecting Information

The SCS will be administered to all NCVS respondents ages 12 to 18 during the 6-month period from January through June 2025. For the 6-month period, January through June 2025, the NCVS will be administered to approximately 130,000 designated households. The NCVS uses a rotating sample that consists of seven groups for each month of enumeration. Each HU selected for the NCVS remains in the sample for three years, with each of seven interviews taking place at 6-month intervals.

The Control Card (NCVS-500) is used to complete a household roster with names and other demographic information of the household members. For some demographic questions that are asked directly of respondents, flashcards are used, such as for education, race, Hispanic origin, employment, and household income.

Respondents are asked to report victimization experiences occurring in the six months preceding the month of interview. The NCVS-1 is asked of all respondents age 12 years or older in the household and is used to ascertain whether the respondent has experienced a personal crime victimization during the prior six months and is therefore eligible to be administered the NCVS Crime Incident Report instrument (NCVS-2). The NCVS-1 collects the basic information needed to determine whether the respondent experienced a crime victimization (rape or other sexual assault, robbery, aggravated or simple assault, personal larceny, burglary, motor vehicle theft, other types of household theft, or vandalism).

When a respondent reports an eligible personal victimization, the NCVS-2 is then administered to collect detailed information about the crime incident. The NCVS-2 is administered for each incident the respondent reports. For each victimization incident, the NCVS-2 collects information about the offender (e.g., sex, race, Hispanic origin, age, and victim-offender relationship), characteristics of the crime (including time and place of occurrence, use of weapons, nature of injury, and economic consequences), whether the crime was reported to police, reasons the crime was not reported, and victim experiences with the criminal justice system. Clearance for the core NCVS forms and materials including the NCVS-500, NCVS-1 and NCVS-2 are requested through a separate OMB request and number (OMB Control No: 1121-0111). Once the NCVS interview is completed (i.e. nonvictims responded to all NCVS-1 screening questions or victims completed all necessary NCVS-2 incident reports), the interviewer administers the SCS questionnaire to persons ages 12 to 18.

If the interview occurs during the first contact with a household that is new to the sample, the interview is typically conducted in person. Households that have been previously interviewed and are in their second through seventh interview can be interviewed by telephone whenever possible. A little over half (51%) of all interviews conducted each month are by telephone.

SCS collection

The SCS is designed to calculate national estimates of school-related victimization for the target population – all youth ages 12 to 18 living in U.S. households who attended public or private school, or a homeschool cooperative in person, and were enrolled in grades 6-12 during the current school year.

Initially, each eligible person ages 12 to 18 is asked a short set of screener questions to determine if they attended school, either private or public, at any time during the current school year. Respondents are also asked if they were homeschooled or attended a homeschool cooperative during the current school year. Students are ineligible if they were homeschooled the entire survey period, did not attend a homeschool cooperative in person, or if they were enrolled in a grade below 6^th, a GED program, or in college. If they did meet the school criteria, the students are then administered the SCS core instrument.

As in prior years, the 2025 SCS responses will be linked to the NCVS survey instrument responses for a more complete understanding of the individual student’s experiences with victimization outside of the school environment. Demographic and household characteristics of the individual student can also be examined through this linking. This integration of the two surveys allows for a more complete understanding of individual students’ circumstances and the relationships between victimization in and out of school.

3. Methods to Maximize Response

Contact Strategy

The Census Bureau mails notifications to households prior to data collection, interviewers contact households for the first time in-person, and interviewers conduct nonresponse follow-up. The Census Bureau mails an introductory letter (NCVS-572(L)) explaining the NCVS to the household before the interviewer's visit or call (Attachment 5). During the SCS data collection months, Census also mails an SCS parent and student (English) brochure (Attachment 7, will be updated to reflect 2022 estimates) to each NCVS household with their NCVS letter. When they go to a household, the interviewers carry cards identifying them as Census Bureau employees. Potential respondents are assured that their answers will be held in confidence and are only used for statistical purposes. For respondents who have questions about the NCVS, interviewers provide a brochure (NCVS-110), and can also reference the frequently asked questions and answers tab in the CAPI instrument. At the field representative (FR)’s discretion, a thank you letter is sent to the household (NCVS-593(L)). All forms and materials used for contact with the household have been previously approved by OMB (OMB Control No: 1121-0111).

The Census Bureau trains interviewers to obtain respondent cooperation and instructs them to make repeated attempts to contact respondents and complete all interviews. The interviewer obtains demographic characteristics of noninterview persons for use in the adjustment for nonresponse. SCS response rates are monitored on a monthly basis and compared to the previous month’s average to ensure their reasonableness.

As part of their job, interviewers are instructed to keep noninterviews, or nonresponse from a household or persons within a household, to a minimum. Household nonresponse occurs when an interviewer finds an eligible household but obtains no interviews. Person nonresponse occurs when an interview is obtained from at least one household member, but an interview is not obtained from one or more other eligible persons in that household. Maintaining a high response rate involves the interviewer’s ability to enlist cooperation from all kinds of people and to contact households when people are most likely to be home.

As part of their initial training, interviewers are exposed to ways in which they can persuade respondents to participate as well as strategies to use to avoid refusals. Furthermore, the Census office staff makes every effort to help interviewers maintain high participation by suggesting ways to obtain an interview, and by making sure that sample units reported as noninterviews are in fact noninterviews. Also, survey procedures permit sending a letter to a reluctant respondent as soon as a new refusal is reported by the interviewer to encourage their participation and to reiterate the importance of the survey and their response. For the 2025 SCS, Census regional offices will send SCS-specific letters to parents to encourage their child’s participation in the survey (see Attachment 8, will be updated prior to distribution).

The SCS specific letter and brochures have been distributed during prior SCS administrations and will provide answers to frequently asked questions about the SCS, and they will be produced in both English and Spanish. The student brochure includes the answers to such questions as “Do I have to take this survey?” and “Why are my answers to the survey important?” The parent brochure includes answers to such questions as “What is the purpose of this survey?” and “What questions are on the survey for my child?” The parent brochure will also include some illustrative survey findings from the SCS. Findings will not be included on the student brochure out of concern that they might bias student responses.

Interviewer Training

Training for NCVS interviewers consists of classroom and on-the-job training. Initial training for new interviewers consists of a full day pre-classroom self-study, four-day classroom training, post-classroom self-study, and on-the-job observation and training. Initial training includes topics such as protecting respondent confidentiality, gaining respondent cooperation, answering respondent questions, proper survey administration, use of systems to collect and transmit survey data, NCVS concepts and definitions, and completing simulated practice NCVS interviews. The NCVS procedures and concepts taught in initial training are also regularly reinforced for experienced NCVS interviewers. This information is received via monthly written communications, ongoing feedback from observations of interviews by supervisors, and monthly performance and data quality feedback reports.

NCVS interviewers also receive specific training on the SCS including eligibility, the organization of the SCS interview, content of the survey questionnaire, addressing potential respondent questions, and internal check items that are in place to help the interviewer ensure that the respondent is being asked the appropriate questions and follow-up when clarification is needed. Interviewers receive a self-study training manual that they are required to read and they must complete a Final Review Exercise to verify their knowledge of the concepts presented in the self-study training manual. The SCS training materials are distributed to interviewers electronically on their Census laptop approximately one month before the supplement goes into the field.

Census Regional Offices (ROs) will host a kick-off meeting prior to data collection and again halfway through data collection. Regular meetings during data collection with FRs will also be held to emphasize the importance of the SCS. These meetings will provide the opportunity for FRs to share feedback and share best practices for completing interviews with SCS eligible respondents.

Monitoring Interviewers

In addition to the above procedures used to ensure high participation rates, the Census Bureau implements additional performance measures for interviewers based on data quality standards. Interviewers are trained and assessed on administering the NCVS-1, NCVS-2, and SCS exactly as worded to ensure the uniformity of data collection, completing interviews in an appropriate amount of time (not rushing through them), and keeping item nonresponse and “don’t know” responses to a minimum. The Census Bureau also uses quality control methods to ensure that accurate data are collected. Interviewers are continually monitored by their regional office to assess whether performance and response rate standards are being met and corrective action is taken to assist and discipline interviewers who are not meeting the standards.

Reinterview is a major feature of both the quality assurance (QA) and the missed crimes estimation program. The NCVS QA reinterview uses two approaches: random and supplemental (supervisor discretion) to validate interviewer performance. The missed crimes estimation program uses the data from the QA program to estimate household and person level missed crimes. The random reinterview approach consists of selecting a sample of each interviewer’s work to review over the data collection cycle. The supplemental approach allows supervisors to identify additional interviewers or cases for review throughout the cycle.

Reinterview requires that a supervisor or experienced interviewer re-contact respondents at a sample of previously-interviewed households. Reinterviewers verify that the original interviewer contacted the correct sample unit, determined the correct household composition, and classified noninterview households correctly. Reinterviewers also verify the household roster and tenure, ensure specific questions are covered, and re-ask a subset of the crime screener questions.

Another component of the data quality program is monthly feedback. In 2011, the Census Bureau implemented a series of field performance and data quality indicators. Previously, high response rates were the primary measure of interviewer performance. The data quality indicators are tracked through the Census Bureau’s expanded Performance and Data Analysis (Giant PANDA) tool, and monthly reports provided to the field. Under the revised performance structure, interviewers are monitored on the following –

• response rates (household, person, and the current supplement in the field);

• time stamps (the time it takes to administer the screener questions on the NCVS-1 or the crime incident questions on the NCVS-2);

• overnight starts (interviews conducted very late at night or very early in the morning);

• late starts (cases not started until the 15th or later in the interview month);

• absence of contact history records (cases missing records of contact attempts with the household and/or persons within the household); and

• quality of crime incidents (changes made to the location, presence, or theft data items on the NCVS-2 during post-processing coding operations).

Noncompliance with these indicators results in supervisor notification and follow-up with the interviewer. The follow-up activity may include simple points of clarification (e.g., the respondent works nights and is only available in the early morning for an interview), additional interviewer training, or removal of the interviewer from the survey.

Every effort has been made to make the survey materials clear and straightforward. The SCS instrument has been designed to make collection of the data as concise and easy for the respondent as possible. The SCS questions have been cognitively tested to ensure that they are easily understood by most respondents.

Nonresponse and Response Rates

In 2022, interviewers were able to obtain NCVS interviews with about 82% of household members in 64% of the occupied units in sample in a given month. The interviewers are trained to make repeated attempts at contacting respondents and to complete interviews with all eligible households. Annually, the Census Bureau conducts a complete analysis of nonresponse. Since 2018, the Census Bureau reports nonresponse and response rates, respondent and nonrespondent distribution estimates, and proxy nonresponse bias estimates for various subgroups. Should the analyses reveal evidence of nonresponse bias, BJS will work with the Census Bureau to assess the impact to estimates and ways to adjust the weights accordingly. The interviewers obtain demographic characteristics of noninterview persons for use in the adjustment for nonresponse.

In 2022, the Census Bureau found evidence of potential bias in the SCS estimates because the overall response rate was low. Analysis indicated that respondent and nonrespondent distributions were significantly different for age and census region subgroups. However, after applying weights adjusted for person nonresponse, there was no evidence that these response differences introduced nonresponse bias in the final victimization estimates.

4. Testing of Procedures

No cognitive testing was completed prior to the 2025 SCS administration. The minor revisions to the questionnaire used language from existing federal surveys interviewing youth including the National Survey on Drug Use and Health and Youth Risk Behavior Survey. Prior to releasing the CAPI instrument for administration, Census conducts comprehensive and systematic user testing.

5. Consultants on Statistical Aspects of the Design

BJS and NCES take responsibility for the overall design and management of the activities described in this submission, including developing study protocols, sampling procedures, and questionnaires and overseeing the conduct of the studies and analysis of the data by contractors.

The Census Bureau will collect all information. John Gloster is the NCVS Survey Director at the Census Bureau and manages and coordinates the NCVS and its supplements. David Hornick of the Census Bureau’s Demographic Statistical Methods Division oversees the statistical aspects of the supplement. BJS, NCES, and Census Bureau staff responsible for the SCS include –

BJS Staff: all staff located at- 810 7th Street, NW Washington, DC 20531	NCES Staff: all staff located at- 550 12th Street, SW Washington, DC 20202	Census Bureau Staff: all staff located at- 4600 Silver Hill Road Suitland, MD 20746
Kevin M. Scott, Ph.D. Acting Director	Gail M. Mulligan, Ph.D. Chief Statistician	John Gloster NCVS Survey Director Associate Directorate for Demographic Programs – Survey Operations
Shelley S. Hyland, Ph.D. Senior Statistical Advisor	Chris Chapman Associate Commissioner Sample Surveys Division	Megan Ruhnke NCVS Assistant Survey Director Associate Directorate for Demographic Programs – Survey Operations
Heather Brotsos Deputy Director of Statistical Programs	Andrew Zukerberg Chief Cross-Sectional Surveys Branch	Chris Seamands NCVS Assistant Survey Director Associate Directorate for Demographic Programs – Survey Operations
Rachel E. Morgan, Ph.D. Chief Victimization Statistics Unit	Deanne Swan, Ph.D. Senior Technical Advisor	Scott Raudabaugh Chief, Crime Surveys Programming & Population Support Branch Chief Demographic Surveys Division
Alexandra Thompson Statistician Victimization Statistics Unit	Michael McGarrah, Ph.D. Statistician Study Director for Crime and Safety Surveys	David Hornick Lead Scientist Demographic Statistical Methods Division

1 Public schools are identified on the Department of Education’s (ED) Common Core of Data (CCD) database (https://nces.ed.gov/ccd/). Charter schools are included in the CCD database and therefore are categorized as public schools. Private schools are identified on ED’s Private School Universe Survey (PSS) (https://nces.ed.gov/surveys/pss/).

2 Homeschooling cooperatives (co-ops) are groups of homeschooling families who work together to educate their children. They can range from informal groups to more formal programs that resemble private schools. Some co-op students attend this type of schooling in person.

3 For a more complete description of the 2010-based sample design, see National Crime Victimization Survey, Technical Documentation, NCJ 251442.

4 Ohlsson, Esbjorn (2000). Coordination of PPS Samples Over Time. In The Second International Conference on Establishment Surveys, American Statistical Association, 255-264.

5 Table 1. Annual Estimates of the Resident Population for the United States, Regions, States, and Puerto Rico. July 1, 2010 to July 1, 2019 (NST-EST2019-01). Source: U.S. Census Bureau, Population Division. Release Date: December 2019.

6 Criminal Victimization in the 22 Largest U.S. States, 2017-2019 (NCJ 305402, March 2023).

7 Everitt, B.S., and Skrondal, A. (2010). The Cambridge Dictionary of Statistics, Fourth Edition. Retrieved from http://www.stewartschultz.com/statistics/books/Cambridge%20Dictionary%20Statistics%204th.pdf.

8 User's Guide to The National Crime Victimization Survey (NCVS) Generalized Variance Functions (GVF).

7