"This first guidance note, Introduction to Impact Evaluation, provides an overview of impact evaluation, explaining how impact evaluation differs from – and complements – other types of evaluation, why impact evaluation should be done, when and by whom. It describes different methods, approaches ... and designs that can be used for the different aspects of impact evaluation: clarifying values for the evaluation, developing a theory of how the intervention is understood to work, measuring or describing impacts and other important variables, explaining why impacts have occurred, synthesizing results, and reporting and supporting use. The note discusses what is considered good impact evaluation – evaluation that achieves a balance between the competing imperatives of being useful, rigorous, ethical and practical – and how to achieve this. Footnotes throughout the document contain references for further reading in specific areas." (Introduction, page 1) more

"Since impact evaluations focus on results and what contributes to results, logically there should be a greater enthusiasm for making use of the findings. Impact evaluations also tend to cost more than other types of evaluation, implying that they should command significant follow up as well. It tur ... ns out, however, that credible evidence and significant costs are not sufficient to ensure that impact evaluation findings are used. This guidance note looks to several additional factors that contribute to effective evaluation use. Using impact evaluations depends importantly on how one designs and conducts them. As was illustrated in Guidance Note 3 on mixed methods, the choice of evaluation method should follow from the questions one is trying to answer. But whatever questions are being tackled, whatever evaluation methods are employed, to make the best and proper use of evaluation findings we can apply a common set of practices and insights." (Introduction) more