Randomization in the Tropics Revisited: a Theme and Eleven Variations

Randomized controlled trials have been used in economics for 50 years, and intensively in economic development for more than 20. There has been a great deal of useful work, but RCTs have no unique advantages or disadvantages over other empirical methods in economics. They do not simplify inference, nor can an RCT establish causality. Many of the difficulties were recognized and explored in economics 30 years ago, but are sometimes forgotten. I review some of the most relevant issues here. The most troubling questions concern ethics, especially when very poor people are experimented on. Finding out what works, even if such a thing is possible, is in itself a deeply inadequate basis for policy