This MECHANISMS study investigates how social norms for adolescent smoking and vaping are transmitted through school friendship networks using behavioral economics methodology. The study examines the effects of selection homophily (choosing friends with similar traits) and peer influence on experimentally measured smoking/vaping norms and other smoking outcomes in adolescents from high (Northern Ireland) and middle (Bogotá, Colombia) income settings. Results show significant selection homophily and peer influence effects, with SIENA models indicating comparable contributions from both mechanisms. Differences in the relative importance of selection homophily and peer influence were observed across settings and intervention programs (ASSIST vs. Dead Cool). These findings support the use of social norms strategies in adolescent smoking prevention.

Jennifer M. Murray, Sharon C. Sánchez-Franco, Erik O. Kimbrough, Christopher Tate, Shannon C. Montgomery, Rajnish Kumar, Laura Dunne, Abhijit Ramalingam, Erin L. Krupka, Felipe Montes, Huiyu Zhou, Laurence Moore, Linda Bauld, Blanca Llorente, Frank Kee, Ruth F. Hunter