The 1/d law of giving

We combine survey data on friendship networks and individual characteristics with experimental observations from dictator games. Dictator offers are primarily explained by social distance, giving follows a simple inverse distance law. While student demographics play a minor role in explaining offer amounts, individual heterogeneity is important for network formation. In particular, we detect significant homophilous behavior; students connect to others similar to themselves. Moreover, the network data reveal a strong preference for cliques, students connect to those already close. The study is one of the first to identify network architecture with individual behavior in a strategic context.