What’s the empirical evidence that RCTs actually improve policy?  Incisive comments from the noble Lant Pritchett:

The argument that RCTs would be more than a tiny component of the overall process of improving development outcomes seems, even now, 10 years in, at best not provable and at worst not very likely—as it is at odds with some basic known facts about development and about policy formulation and implementation.

What “basic known facts” does he have in mind?  First, RCTs can’t be crucial ...