With rigorous economic research and practical policy solutions, we focus on the issues and institutions that are critical to global development. Explore our core themes and topics to learn more about our work.
In timely and incisive analysis, our experts parse the latest development news and devise practical solutions to new and emerging challenges. Our events convene the top thinkers and doers in global development.
The recent wave of randomized trials in development economics has provoked criticisms
regarding external validity. We investigate two concerns—heterogeneity across beneficiaries and
implementers—in a randomized trial of contract teachers in Kenyan schools. The intervention,
previously shown to raise test scores in NGO-led trials in Western Kenya and parts of India, was
replicated across all Kenyan provinces by an NGO and the government. Strong effects of short-term
contracts produced in controlled experimental settings are lost in weak public institutions:
NGO implementation produces a positive effect on test scores across diverse contexts, while
government implementation yields zero effect. The data suggests that the stark contrast in success
between the government and NGO arm can be traced back to implementation constraints and
political economy forces put in motion as the program went to scale.