Due to incomplete contracts, efficiency of an organization depends on willingness of individuals to take non-selfish actions, such as cooperating when there is no incentive to do so or punishing inefficient actions by others. Organizations also constitute a social boundary, or group. We...

"This paper considers the semiparametric identification of endogenous and exogenous peer effects based on group size variation. We show that Lee (2006)'s linear-in-means model is generically identified, even when all members of the group are not observed. While unnecessary in general,...