Peer Effects on Mental Health: Evidence from Random Assignment into Classrooms

Abstract

Adolescent mental health has wide-ranging and long-lasting socio-economic consequences. Existing evidence based on observational data of friendship networks points to a positive correlation between an individual's mental health and her peers', but concerns remain whether this link is causal. I study whether there exist peers effects on mental health in the classroom, by exploiting variations in peer composition generated by assignment rules in junior secondary schools in China, where students are randomly or evenly grouped into classrooms. In general I find no evidence of overall peer effects, and weak evidence of context-specific peer effects when taking into account heterogeneity and non-linearity. From a policy perspective, the general weakness of peer effects suggests that group-based interventions at the classroom level probably would not generate large positive externality.