We estimate the impact on pilgrims of performing the Hajj pilgrimage to Mecca. Our method compares successful and unsuccessful applicants in a lottery used by Pakistan to allocate Hajj visas. Pilgrim accounts stress that the Hajj leads to a feeling of unity with fellow Muslims, but outsiders...

This paper proposes a production function describing processes subject to mistakes in any of several tasks. It shows that high-skill workers--those who make few mistakes--will be matched together in equilibrium, and that wages and output will rise steeply in skill. The model is consistent with...

We use a randomized evaluation of a Kenyan deworming program to estimate peer effects in technology adoption and to shed light on foreign aid donors' movement towards sustainable community provision of public goods. Deworming is a public good since much of its social benefit comes through...

In 1839 the French government purchased the Daguerreotype patent and placed it in the public domain. Such patent buyouts could potentially eliminate the monopoly price distortions and incentives for rent-stealing duplicative research created by patents, while increasing incentives for original...

The nonrivalry of technology, as modeled in the endogenous growth literature, implies that high population spurs technological change. This paper constructs and empirically tests a model of long-run world population growth combining this implication with the Malthusian assumption that technology...

Increased HIV risk creates incentives for people with low sexual activity to reduce their activity but may make high-activity people fatalistic, leading them to reduce their activity only slightly or actually increase it. If high-activity people reduce their activity by a smaller proportion than...

Under central planning, many firms relied on a single supplier for critical inputs. Transition has led to decentralized bargaining between suppliers and buyers. Under incomplete contracts or asymmetric information, bargaining may inefficiently break down and, if chains of production link many...

Using a randomized evaluation in Kenya, we measure health impacts of spring protection, an investment that improves source water quality. We also estimate households' valuation of spring protection and simulate the welfare impacts of alternatives to the current system of common property rights...

Some commentators argue that increased sorting into internally homogeneous neighborhoods, schools, and marriages is radically polarizing society. Calibration of a formal model, however, suggests that the steady-state standard deviation of education would increase only 1.7 percent if the...