Why are some more peer than others? Evidence from a longitudinal study of social networks and individual academic performance

► Analysis of peer effects in educational settings. ► Longitudinal data on academic performance, friendship, and advice relations among MBA students. ► Process of peer selection modelled by actor-oriented models. ► Social influence operates similarly for friendship and advice networks. ► High performers are less likely to initiating ties, to be chosen as friends but are sought after as advisors. Studies of peer effects in educational settings confront two main problems. The first is the presence of endogenous sorting which confounds the effects of social influence and social selection on individual attainment. The second is how to account for the local network dependencies through which peer effects influence individual behavior. We empirically address these problems using longitudinal data on academic performance, friendship, and advice seeking relations among students in a full-time graduate academic program. We specify stochastic agent-based models that permit estimation of the interdependent contribution of social selection and social influence to individual performance. We report evidence of peer effects. Students tend to assimilate the average performance of their friends and of their advisors. At the same time, students attaining similar levels of academic performance are more likely to develop friendship and advice ties. Together, these results imply that processes of social influence and social selection are sub-components of a more general a co-evolutionary process linking network structure and individual behavior. We discuss possible points of contact between our findings and current research in the economics and sociology of education.