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
A version of this essay is forthcoming in Florent Bédécarrats, Isabelle Guérin and François Roubaud, Randomized controlled trials in the field of development: a critical perspective, Oxford University Press. For generous and helpful comments on an earlier version, I am most grateful to Nancy Cartwright, Anne Case, Shoumitro Chatterjee, Nicolas Côté, Jean Drèze, William Easterly, Reetika Khera, Lant Pritchett, C. Rammanohar Reddy, François Roubaud, Dean Spears and Bastian Steuwer. This work was in part funded with generous support from the National Institute on Aging through the NBER, Grant number P01AG05842. The views expressed herein are those of the author and do not necessarily reflect the views of the National Bureau of Economic Research.