ABSTRACT
Evaluation identifies the impacts of an intervention program by analysing cause and effect. An impact evaluation assesses the extent to which a program has caused desired changes in the intended audience: it is concerned with the net impact of an intervention on households and institutions, attributable only and exclusively to that intervention. The chapter reviews the key concepts and tools available for conducting sound impact evaluation. Qualitative methods not only provide qualitative measures of impact but also deepen the interpretation of results obtained from a quantitative approach by shedding light on processes and causal relationships. Two methods can be used to identify comparison groups: experimental or quasi-experimental methods and non-experimental methods. Although both experimental and non-experimental methods are grounded in the quantitative approach to evaluation, incorporating qualitative methods enriches the quality of the evaluation results. The choice of a method for establishing controls depends on the design of the program and the particular problem or constraint.
