Local interactions refer to social and economic phenomena where individuals' choices are influenced by the choices of others who are close to them socially or geographically. This represents a fairly accurate picture of human experience. Furthermore, since local interactions imply particular...

Field evidence suggests that agents belonging to the same group tend to behave similarly, i.e., behavior exhibits social interaction effects. Testing for such effects raises severe identification problems. We conduct an experiment that avoids these problems. The main design feature is that each...