Credible impact evaluation in complex contexts: Confirmatory and exploratory approaches

Debate continues over how best international development agencies can evaluate the impact of actions intended to reduce poverty, insecurity and vulnerability in diverse and complex contexts. There are strong ethical grounds for simply asking those intended to benefit what happened to them, but it is not obvious how to do so in a way that is sufficiently free from bias in favour of confirming what is expected. This article considers scope for addressing this problem by minimising the prior knowledge participants have of what is being evaluated. The tensions between more confirmatory and exploratory methodological approaches are reviewed in the light of experience of designing and piloting a qualitative impact assessment protocol for evaluating NGO interventions in complex rural livelihood transformations. The paper concludes that resolving these tensions entails using mixed methodologies, and that the importance attached to exploratory (nested within confirmatory) approaches depends on contextual complexity, the type of evidence sought and the level of trust between stakeholders.