We characterize optimal urban transportation policies in the presence of congestion and environmental externalities and evaluate their welfare and distributional effects. We present a framework of a municipal government that implements different transportation equilibria through its choice of...

Online marketplaces have adopted new quality control mechanisms that can accommodate a flexible pool of providers. In the context of ride-hailing, we measure the effectiveness of these mechanisms, which include ratings, incentives, and behavioral nudges. Using telemetry data as an objective...

Vaccinating the world's population quickly in a pandemic has enormous health and economic benefits. We analyze the problem faced by governments in determining the scale and structure of procurement for vaccines. We analyze alternative approaches to procurement. We find that if the goal is to...

Drug traffickers sometimes share profits peacefully. Other times they fight. We propose a model to investigate this variation, focusing on the role of the state. Seizing illegal goods can paradoxically increase traffickers' profits, and higher profits fuel violence. Killing kingpins makes crime...

In the last decade, new technologies have led to a boom in real-time pricing. I analyze the most salient example, surge pricing in ride hailing. Using data from Uber, I develop an empirical model of spatial equilibrium to measure the welfare effects of surge pricing. The model is composed of...

We review economic arguments for using public policy to accelerate vaccine supply during a pandemic. Rapidly vaccinating a large share of the global population helps avoid economic, mortality, and social losses, which in the case of Covid-19 mounted into trillions of dollars. However,...