Participants at the age-11 and age-14 assessments were assessed with a computerized questionnaire. The exact question was “During the past 12 months, about how many cigarettes did you smoke in a day when you did smoke?” Participants responded on a 7-point scale. Assessments at later ages were conducted in-person by extensively trained research assistants using a modified version of the expanded Substance Abuse Module (SAM; (Robins, Babor, & Cottler, 1987)). The exact question on the SAM was “During the past 12 months, how much have you smoked (tobacco have you used) on a typical day that you smoked (used tobacco)?” Respondents gave an integer number in response. The computerized questionnaire responses were converted to an integer number for concordance with the SAM. CPD measures were log transformed for all analyses (except descriptive analyses) to mitigate the effect of extreme values on parameter estimates. Frequency of drinking alcohol was also measured with a computerized questionnaire (“During the past 12 months, about how many times did you drink alcohol?”) at age 11 and 14 and the SAM (“In the past 12 months,
