Multistage area probability sample design involving three election stages: (1) geographic areas or primary sampling units (PSUs), (2) schools (or linked groups of schools) within PSUs, and (3) students within sampled schools. Separate samples were drawn for each grade. Of the 80 PSUs, 8 were selected with certainty and 72 were selected with probability proportionate to size based on the size of the 8th- (or 10th-) grade class in each school. In schools with more than 400 8th (or 10th) graders, a random sample of students or classes was drawn. In schools with less than 400 8th (or 10th) graders, all students were asked to participate. Each sampled school was asked to participate for two years, so that each year one-half of the sample is replaced. Schools refusing participation were replaced with similar schools in terms of geographic location, size, and type of school (e.g., public, private/Catholic, private/non-Catholic). For the 8th-grade survey, schools with less than 15 8th graders were excluded from the sample. For the 10th-grade survey, schools with less than 25 10th graders were excluded. The participation rate among schools has been between 66 and 80 percent since the inception of the study. The student response rates for the 1999 8th- and 10th-grade surveys were 87 percent and 85 percent, respectively.

To protect the anonymity of respondents, all variables that could be used to identify individuals have been collapsed or recoded in the public use files. These modifications should not affect analytic uses of the public use files. Two year-to-year cross-time question indices for the MTF 8th- and 10th-grade surveys can be viewed on the SAMHDA Web site. The first is sorted by question location and the second is sorted by subject area, item number, and questionnaire form. MTF does not release detailed geography codes in its public use files because of the disclosure risk it would cause. The MTF sample is drawn to generate representative samples of the four Census Bureau regions of the country (Northeast, Midwest, South, and West), but it does not generate representative samples of smaller geographic areas such as states, counties, or cities. For additional information about data that is withheld from the public use files please contact MTF directly at mtfinformation@umich.edu.

These surveys of 8th- and 10th-grade students are part of a series that explores changes in important values, behaviors, and lifestyle orientations of contemporary American youth. Students in each grade are randomly assigned to complete one of four questionnaires, each with a different subset of topical questions but containing a set of "core" questions on demographics and drug use. There are about 300 variables across the questionnaires. Drugs covered by this survey include amphetamines (stimulants), barbiturates (tranquilizers), other prescription drugs, tobacco, alcohol, inhalants, steroids, marijuana, hashish, LSD, hallucinogens, cocaine, crack, and injection drugs such as heroin.

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 recodes and/or calculated derived variables.; Checked for undocumented or out-of-range codes..

Datasets: DS0: Study-Level Files DS1: 8th-Grade Form 1 Data DS2: 8th-Grade Form 2 Data DS3: 8th-Grade Form 3 Data DS4: 8th-Grade Form 4 Data DS5: 10th-Grade Form 1 Data DS6: 10th-Grade Form 2 Data DS7: 10th-Grade Form 3 Data DS8: 10th-Grade Form 4 Data

Enrolled 8th- and 10th-grade students in the contiguous United States.

Monitoring the Future (MTF) Series