The sample was comprised of participants in the 2001–2002 National Epidemiologic Survey on Alcohol and Related Conditions (NESARC), a nationally representative United States survey of civilian non-institutionalized participants aged 18 and older, interviewed in person. The National Institute on Alcohol Abuse and Alcoholism (NIAAA) sponsored the study and supervised the fieldwork, conducted by the U.S. Bureau of the Census. The NESARC used a multistage stratified design in which primary sampling units (PSUs) were stratified according to certain sociodemographic criteria. The sampling frame for housing units is the Census 2000/2001 Supplementary Survey (C2SS) and that for group quarters is the Census 2000 Group Quarters Inventory. The C2SS sample of 655 PSUs was selected at the first stage, including 401 self-representing (SR) and 254 non-self-representing (NSR) PSUs. All SR PSUs were selected with certainty. For the NSR sample, two PSUs were selected per stratum, with probability proportional to the size of the estimated 1996 population of the stratum. At the second stage, housing units and group quarter units (converted to housing unit equivalents) were systematically selected within the PSUs. Non-Hispanic Black and
