Data gathered on lifetime substance experimentation and repeated-use were collected using a MTF-based (Johnston et al., 1986) self-report questionnaire. Data on abuse and dependence were collected using the Composite International Diagnostic Interview-Substance Abuse Module (CIDI-SAM) structured interview (Cottler et al., 1989; Üstűn et al., 1997). The CIDI-SAM is a face-to-face interview administered by lay interviewers that has been demonstrated to be a reliable and useful diagnostic tool for gathering data on drug abuse and dependence in both clinical and general research settings (Cottler et al., 1989; Crowley et al., 2001; Üstűn et al., 1997). At Wave 1, the CIDI-SAM was administered using a paper and pencil interview protocol while at Wave 2 a computerized version was employed.
