This study reports the findings from a year-long randomized evaluation assessing the impact of assigning 62 classrooms in Nigeria to receive either blocked or interleaved math problem sets. Blocked practice sessions focused on a single skill at a time. Interleaved problem sets alternated between...

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...

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...

Ten years ago, donors committed $1.5 billion to a pilot Advance Market Commitment (AMC) to help purchase pneumococcal vaccine for low-income countries. The AMC aimed to encourage the development of such vaccines, ensure distribution to children in low-income countries, and pilot the AMC...

We assess evidence from randomized control trials (RCTs) on long-run economic productivity and living standards in poor countries. We first document that several studies estimate large positive long-run impacts, but that relatively few existing RCTs have been evaluated over the long-run. We next...

Following the widespread adoption of free primary education, African policymakers are now considering making secondary school free, but little is known about the private and social benefits of free secondary education. We exploit randomized assignment to secondary school scholarships among 2,064...

Each year, around 500,000 children under 5 die from diarrhea, making it the third-leading cause of death in this age group. More than 80 percent of these deaths are attributable to unsafe drinking water. Drinking water can be made safe through dilute chlorine solution, but take-up of this...

Empirical tests in the 1990s found little evidence of poor countries catching up with rich - unconditional convergence - since the 1960s, and divergence over longer periods. This stylized fact spurred several developments in growth theory, including AK models, poverty trap models, and the...

Millions of people are being vaccinated against SARS-CoV-2 every day, but the virus is also mutating and spreading fast. Vaccine production is increasing, but supply still constrains vaccinations worldwide. Using lower doses of vaccines could dramatically accelerate vaccination. Available...