Should the Randomistas (Continue to) Rule? - Working Paper 492

August 16, 2018

This version: January 2019

The rising popularity of randomized controlled trials (RCTs) in development applications has come with continuing debates about the merits of this approach. The paper takes stock of the issues. While RCTs have an important place in the toolkit for impact evaluation, an unconditional preference for RCTs as the “gold standard” is questionable on three main counts. First, the case for such a preference is unclear on a priori grounds; indeed, for a given budget, even a biased observational study may well come closer to the truth than an RCT. Second, the ethical objections to RCTs call for a stronger defense than is commonly found at present. Third, there is a serious risk of distorting the evidence-base for informing development policymaking, given that an insistence on doing RCTs generates selection bias in what gets evaluated. Going forward, pressing knowledge gaps should drive the questions asked and how they are answered, not the methodological preferences of some researchers. The gold standard is the best method for the question at hand.

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