The norming groups were based on a sampling of housing units, including all such units within the 50 states and the District of Columbia.
Interviewers screened some 75,000 households to determine if there was one or more youth in the proper age range. When this was the case, additional demographic information was collected and the youth(s) were offered $75 to go to a local Sylvan Testing Center and take the CAT-ASVAB. The participation rate was 75 percent among those in the CEP sample, and 77 percent among ETP sample members.
Because each study participant was selected with known probability, it was possible to weight the cases in a way that the weighted sample would reflect the population on the major demographics of interest (age, race/ethnicity, gender, and education).
Download a copy of a report that provides details on the sampling and weighting procedures used. [National Longitudinal Survey of Youth 1997 (NLSY97): Technical Sampling Report]: