We utilized substance use measures that were queried consistently across the four waves of sampling. All measures are based on the self-report of the respondent. Measures of self-reported substance use have well-documented reliability and validity (Buchan et al., 2002; Midanik, 1988; Patrick et al., 1994), especially when asked over short, recent time frames. We utilized measures of substance use in the past 30 days and past year.
