We examine a randomized trial that allows separate identification of peer screening and enforcement of credit contracts. A South African microlender offered half its clients a bonus for referring a friend who repaid a loan. For the remaining clients, the bonus was conditional on loan approval....

We seed noisy information to members of a real-world social network to study how information diffusion and information aggregation jointly shape social learning. Our environment features substantial social learning. We show that learning occurs via diffusion which is highly imperfect: signals...

This Paper uses a unique dataset collected among inhabitants of Amsterdam, to study the dynamics in the consumption of cannabis and cocaine. If people start using these drugs they are most likely to do so at age 18-20 for cannabis and age 20-25 for cocaine. An analysis of the starting rates...