Impact evaluations are thus primarily a tool for learning and improving development interventions. They are an important part of a broader agenda of evidence-based policy-making – in contrast to ideologically, emotionally or politically driven policies.

For example, impact evaluations have revealed that farmers in developing countries are less constrained by their access to credit than once thought. Instead, a lack of risk coverage (Karlan et al., 2010) or psychological biases (Duflo et al., 2011) appear to be more likely barriers to farmers investing in new crops and innovative technology. Such insights are of great value to policy-makers looking for effective measures to assist farmers in adopting new technologies.

Besides providing insights for policy-makers and development practitioners, impact evaluations first of all benefit the poor. While critics argue that experimentation on the poor is unethical, it is also evidently unethical to intervene in the lives of the poor without understanding the changes, intended or unintended, that these interventions are likely to bring about.

Impact evaluations – a new buzzword?

Thanks to technological progress in data collection and the ever-increasing availability of data as well as the creation of various institutions promoting impact evaluations, the number of them being conducted has risen rapidly over the last two decades (see Figure on page 8).