The NESARC-III target population was the noninstitutionalized civilian population ≥18 years in households and selected group quarters (37, 38). Respondents were selected through multistage probability sampling, including primary sampling units (counties/groups of contiguous counties); secondary sampling units (SSU - groups of Census-defined blocks); and tertiary sampling units (households within SSUs from which respondents were selected, with Blacks, Asians, and Hispanics oversampled. Data were collected April 2012–June 2013, and analyzed May-June, 2015. Data were adjusted for nonresponse and weighted to represent the U.S. population based on the 2012 American Community Survey (39). These weighting adjustments compensated adequately for nonresponse (38). The total sample size was 36,309: household response rate was 72%; person-level response rate, 84%, and overall response rate, 60.1% comparable to other current U.S. national surveys (40, 41). NESARC-III sample characteristics are presented elsewhere (38). Informed consent was electronically recorded; respondents received $90.00 for participation. Institutional review boards at the National Institutes of Health and Westat (NESARC-III contractor) approved the study protocol.
