An enduring puzzle regarding technology adoption in developing countries is that new technologies often diffuse slowly through the social network. Two of the key predictions of the canonical epidemiological model of technology diffusion are that forums to share information and higher returns to...

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,...

Randomized controlled trials (RCTs) of water treatment are typically powered to detect effects on caregiver-reported diarrhea but not child mortality, as detecting mortality effects requires prohibitively large sample sizes. Consequently, water treatment is seldom included in lists of...

Mobile phone-based informational programs are widely used worldwide, though there is little consensus on how effective they are at changing behavior. We present causal evidence on the effects of six agricultural information programs delivered through text messages in Kenya and Rwanda. The...

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...