We study collective decisions by time-discounting individuals choosing a common consumption stream. We show that with any heterogeneity in time preferences, utilitarian aggregation necessitates a present bias. In lab experiments three quarters of "social planners" exhibited present biases, and...

In contexts ranging from public goods provision to information collection, a player's well-being depends on his or her own action as well as on the actions taken by his or her neighbours. We provide a framework to analyse such strategic interactions when neighbourhood structure, modelled in...

We examine friendships and study partnerships among university students over several years. At the aggregate level, connections increase over time, but homophily on gender and ethnicity is relatively constant across time, university residences, and different network layers. At the individual...

In a variety of contexts - ranging from public goods provision to information collection - a player's well-being depends on own action as well as on the actions taken by his or her neighbors. We provide a framework to analyze such strategic interactions when neighborhood structure, modeled in...