Starting in the 2013-2014 school year, I conducted a randomized field experiment in fifty traditional public elementary schools in Houston, Texas designed to test the potential productivity benefits of teacher specialization in schools. Treatment schools altered their schedules to have teachers...

We introduce and analyze a model in which agents observe sequences of signals about the state of the world, some of which are ambiguous and open to interpretation. Instead of using Bayes' rule on the whole sequence, our decision makers use Bayes' rule in an iterative way: first to interpret each...

We develop a Roy model of social interactions in which individuals sort into peer groups based on comparative advantage. Two key results emerge: First, when comparative advantage is the guiding principle of peer group organization, the effect of moving a student into an environment with...

Affirmative action policies are practiced around the world. This paper explores the welfare economics of such policies. A model is proposed where heterogeneous agents, distinguished by skill level and social identity, compete for positions in a hierarchy. The problem of designing an efficient...

This paper develops a model of social interactions and endogenous poverty traps. The key idea is captured in a framework in which the likelihood of future social interactions with members of one's group is partly determined by group-specific investments made by individuals. I prove three main...

We introduce a model of two-sided statistical discrimination in which worker and firm beliefs are complementary. Firms try to infer whether workers have made investments required for them to be productive, and simultaneously, workers try to deduce whether firms have made investments necessary...