A debate on approaches to impact evaluation has raged in development circles in recent years. This note gives some reflections on this debate through discussion of four issues. <p> First, it is pointed out that there are two definitions of impact evaluation. Neither one is right or wrong, but they...</p>

Calls for rigorous impact evaluation have been accompanied by the quest not just to find out what works but why. It is widely accepted that a theory based approach to impact evaluation, one that maps out the causal chain from inputs to outcomes and impact and tests the underlying assumptions,...

RCTs have become popular in the development community as part of the response to the results agenda. These studies are well placed to address the question of which programmes work or not. And, properly designed, they can be embedded in a broader evaluation design which also addresses questions...