Following each main effect model, interaction models were estimated for each substance. For the alcohol use and marijuana use models, interaction models were computed by the addition of an interaction term between the latent variables of effortful control and substance use lifestyle. Because the tobacco model retained separate factors for friends’ support of substance use and adolescent tobacco use, two interaction terms were included in the model: Effortful Control × Friends’ Substance Use Support, along with Effortful Control × Adolescent Tobacco Use.
