Several programs have been proposed to improve incentives for research on vaccines for malaria, tuberculosis, and HIV, and to help increase accessibility of vaccines once they are developed. For these programs to spur research, potential vaccine developers must believe that the sponsor will not...

Malaria, tuberculosis, and the strains of HIV common in Africa kill approximately 5 million people each year. Yet research on vaccines for these diseases remains minimal largely because potential vaccine developers fear that they would not be able to sell enough vaccine at a sufficient price to...

Social commentators from William Julius Wilson to Charles Murray have argued that increased sorting of people into internally homogeneous" neighborhoods,schools, and marriages is spurring long-run inequality. Cali- bration of a formal model suggests that these fears are misplaced. In order to...

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...

Under asymmetric information about sexual history, sexual activity creates externalities. Abstinence by those with few partners perversely increases the average probability of HIV infection in the pool of available partners. Since this increases prevalence among the high activity people who...

In a simple representative consumer model, vaccines and drug treatments yield the same revenue for a pharmaceutical manufacturer, implying that the firm would have the same incentive to develop either ceteris paribus. We provide more realistic models in which the revenue equivalence breaks down...

Most government expenditure is on goods that yield primarily private benefits, such as education, pensions, and healthcare. We argue that markets are most advantageous in areas where high-powered incentives are desirable, but in areas where high-powered incentives stimulate unproductive...

Advocates of teacher incentive programs argue that they can strengthen weak incentives, while opponents argue they lead to teaching to the test.' We find evidence that existing teacher incentives in Kenya are indeed weak, with teachers absent 20% of the time. We then report on a randomized...

We prove that, for general demand and cost conditions and market structures, the fraction of first-best surplus that a monopolist is unable to extract in a market provides a tight upper bound on the relative distortions arising from firms' equilibrium decisions at all margins (entry and...

Dynamically and statically optimal Pigouvian subsidies on durables will differ in a growing economy. For durables with positive externalities, such as sanitation, statically optimal subsidies will typically grow. However, in a dynamic game, governments can most cheaply induce optimal purchasing...