The parental monitoring measure asked participants three questions (how much their parent figures know about their plans, interests, and where/with whom they spend time when not at home) from Chassin et al. (1993). Responses were made on a 4-point scale ranging from 1 (Always) to 4 (Rarely), and the inter-item correlations ranged from 0.45-0.56 (all p-values < 0.0001). The four perceived peer substance use questions came from FinnTwin12 (Kaprio, Pulkkinen, & Rose, 2002), and asked participants about how many of their friends smoke, use alcohol, use marijuana, or use other drugs using a 4-point scale ranging from 1 (None of them) to 4 (All of them). The inter-item correlations for the peer substance use questions ranged from 0.45-0.65 (all p-values < 0.0001). Items were summed to create separate parental monitoring and peer substance use composites. Prior to summing, the parental monitoring items were reverse scored so that higher scores indicated more parental monitoring.
