A five-season field experiment with smallholder farmers in sub-Saharan Africa shows that new agricultural technologies are hard to adopt not because farmers lack information, but because such technologies require multiple interdependent decisions that take years of costly trial and error to get right.

Computerising customs at Colombia’s major ports boosted trade, reduced corruption, improved firm performance, and increased tax collections.

Needs-based and merit-based scholarships improve the motivation and social mobility of low-income students

Farmer selection and researcher interference during trials can introduce bias, impacting how new technologies perform in real-world conditions

Data from developing country settings highlight the risk of misinterpreting non-cognitive skills and personality using existing measures

Subsidies need not be permanent to benefit farmers. Well-designed policy that encourages experimentation can generate widespread and lasting impacts.