Participants completed surveys in the 6th, 7th, 8th, 9th, and 11th grades so the extent of their substance use could be assessed throughout an extended developmental period. Separate use scores were created at each assessment point for each substance class evaluated, including tobacco, alcohol, and marijuana. At Grades 6 through 9, participants were asked to report how many cigarettes they had smoked in the past month by using a scale ranging from 0 (0 cigarettes) to 23 (31 or more packs). During these same assessment points, participants were asked to indicate how many drinks of alcohol they had consumed and how many times they had smoked marijuana during the past month by using a scale ranging from 0 (0) to 14 (41 or more). In Grade 11, participants indicated their level of use of tobacco, alcohol, and marijuana by using a scale ranging from 0 (never) to 7 (2–3 times a day [or more]).
