Social network modeling of peer substance use in these data is detailed elsewhere (Osgood, Ragan et al., 2013). Briefly, participants nominated up to two best friends and up to five other close friends in the same grade who also attended the same school. Peer substance use during the 9th grade was based on the nominated peers’ self-reported past month substance use. The substance use measure was based on the mean of four items that addressed how often during the past month the participant (1) drank alcohol, (2) drank enough alcohol to become intoxicated, (3) smoked cigarettes, and (4) used marijuana (1 = Not at all, 5 = More than once a week). Higher scores indicated higher substance use (M(SD) = 1.44(.52)).
