Some Reflections On Current Debates In Impact Evaluation

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. First, it is pointed out that there are two definitions of impact evaluation. Neither one is right or wrong, but they refer to completely different things. There is no point in methodological debates unless they agree a common starting point. Second, there is confusion between counterfactuals, which are implied by the definition of impact evaluation adopted in this paper, and control groups, which are not always necessary to construct a counterfactual. Third, calls for addressing contribution rather than attribution are also definitional, mistaking claims of attribution to mean sole attribution, which is does not. I then consider accusations of being 'positivist' and 'linear', which are, respectively, correct and unclear. Finally, these arguments do not mean that there is a hierarchy of methods, rather that quantitative approaches, including RCTs, are often the best available methods, having the added advantage of allowing analysis of cost effectiveness.