The supplemental sample was meant to over-represent civilian Hispanics, Blacks, and economically disadvantaged Whites. The NLSY79 was administered annually, starting in 1979, then biennially since 1994. In addition to the main questionnaire, which is administered in every year of the survey, other components are administered in some years. NORC fully switched to CAPI in 1993. The only exception to this mode of administration was in 1987, when, due to budget limitations, interviews were given over the phone.
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These individuals made up the final NLSY79 sample. In addition, a few members died. As of 1994, the total sample was comprised of 9964 individuals. In the NLS program, sample members who do not participate in any given year of the survey are still considered members of the sample and can participate in later years. NLSY79 has such low attrition rates over a two-decade period.