Perceived prevalence of peer marijuana use: changes among college students before and after Oregon recreational marijuana legalization

Abstract

Background: Oregon students’ rates of marijuana use have increased following recreational marijuana legalization (RML), but the relation between RML and students’ perceived peer use of marijuana–or descriptive norms–is unknown. Objectives: This study examined whether perceived peer use of marijuana changed more following RML for college students in Oregon than in states without RML. Methods: Repeated cross-sectional data were collected from the National College Health Assessment-II surveys from 2008 to 2016 to assess changes in descriptive norms (“Within the last 30 days, what percent of students at your school used marijuana?”) among 18–26 year-old undergraduates from two Oregon institutions and 123 institutions in non-RML states (N = 280,006; 66.23% female; 33.19% male) following Oregon RML (7/1/2015). Mixed-effects regressions were used to account for clustering at the institutional level; models controlled for covariates and secular changes in descriptive norms. Results: RML was associated with higher perceived rates of marijuana use by peers [Percent Increase = 3.09, p