We combine information on social networks with medical records and survey data in order to examine how friends affect one’s decision to get vaccinated against the flu. The random assignment of undergraduates to residential halls at a large private university allows us to estimate how peer...

There is a longstanding concern that material incentives might undermine prosocial motivation, leading to a decrease in blood donations rather than an increase. This paper provides an empirical test of how material incentives affect blood donations in a large-scale field experiment spanning...

Charitable donations are often made through intermediaries who can fund themselves from these same donations. Donors who purchase charitable output through an intermediary incur a principal-agent problem with unobservable prices. We compare charitable giving in an experiment with and without...

Most economic models are based on the self-interest hypothesis that assumes that all people are exclusively motivated by their material self-interest. In recent years experimental economists have gathered overwhelming evidence that systematically refutes the self-interest hypothesis and suggests...