The modern movement for RCTs in development economics…is about innovation, as well as evaluation. It’s a dynamic process of learning about a context through painstaking on-the-ground work, trying out different approaches, collecting good data with good causal identification, finding out that results do not fit pre-conceived theoretical ideas, working on a better theoretical understanding that fits the facts on the ground, and developing new ideas and approaches based on theory and then testing the new approaches.
This is from an insightful interview with Michael Kremer, Harvard economics professor “generally given credit for launching the RCT movement in development economics with two experiments he led in Kenya in the early 1990s,” and my graduate school advisor.
The interview is in Tim Ogden’s book Experimental Conversations: Perspectives on Randomized Trials in Development Economics.
David Evans' personal blog 