Survey administration procedures have remain unchanged since 1990. Schools are selected using a scientifically-based sampling process, and schools with a large percentage of African American and Hispanic students are over sampled to generate stable estimates each year for these subgroups of youth. The purpose of the survey is to assess the attitudes and behaviors of high school youth in a variety of areas, including and most notably, the areas of drug, alcohol and tobacco use. The survey has been conducted annually among high school seniors since 1975, and has included 8 th and 10 th grade samples annually as well since 1991. The survey is fielded in approximately 435 schools across the country, reflecting a nationally representative sample of both public and private high schools.
Participation is entirely voluntary, and students can refuse to participate if they so wish.
In general, students' responses are confidential, however, respondents do provide some identifying information on a tear-off card. Beginning in 1999, all 8 th and 10 th grade responses are anonymous with no identifying information requested. Moreover, the Household Survey provides the only source of nationally-representative data on adult substance use in this country. The population covered by the survey is the civilian, noninstitutional population age 12 and older in the U.S., including all 50 States and the District of Columbia. The survey incorporates procedures that are likely to increase respondents' cooperation and willingness to report honestly about their illicit drug use behavior.