We randomly assign more than 6,000 students from 150 primary schools in Bangladesh to work on math assignments in one of three settings: individually, in groups with random schoolmates, or in groups with friends. The groups consist of four people and are balanced by average cognitive ability and...

We develop a model where information about jobs is essentially obtained through friends and relatives, i.e. strong and weak ties. Workers commute to a business center to work and to interact with other people. We find that housing prices increase with the level of social interactions in the city...