Firms are more productive on average in larger cities. Two explanations have been offered: agglomeration economies (larger cities promote interactions that increase productivity) and firm selection (larger cities toughen competition allowing only the most productive to survive). To distinguish...

Destination countries have been resorting to selective immigration policies to improve migrants' quality. We propose a model that analyzes the effects of selective immigration policies on migrants' quality, measured by their wages at destination. Screening potential migrants on the basis of...