Using decision trees to examine risk profiles for cannabis use among large samples of underage youth before and after cannabis legalization in Canada

Background: This paper compares risk profiles for cannabis use among large samples of youth in the school years preceding (2017-18, T₁) and four years following (2021-22, T₂) cannabis legalization in Canada. Methods: COMPASS Study data from students across 85 secondary schools that participated in both the T₁ and T₂ waves were used. A novel classification tree approach examined current cannabis use (past 30-day), modelling complex interactions …