Of the 43,093 respondents interviewed at Wave 1, 34,653 respondents were re-interviewed at Wave 2. Census-defined eligible for Wave 2 re-interviews included those not deceased (n=1403), deported, mentally or physically impaired (n=781) or on active military duty (n=950). Sample weights were developed to additionally adjust for Wave 2 non-response. Specifically, weights adjusted for the probabilities of selection of a sample housing unit or housing unit equivalent from the GQ, nonresponse at the household and person levels, the selection of one person per household, and oversampling of young adults. Once weighted, data were adjusted to be representative of the US population for region, age, sex, race, and ethnicity. After adjustment, comparisons between Wave 2 respondents and the target population (comprising Wave 2 respondents and eligible non-respondents) indicated that there were no significant differences in terms of a number of baseline (Wave 1) socio-demographic measures or the presence of any lifetime substance, mood, anxiety or personality disorder (PD) (Grant et al., 2007a). This study examines data of the sub-sample of lifetime nicotine (n=15,918), alcohol (n=28,907), cannabis (n=7,389) or cocaine (n=2,259) users.
