Impact evaluation is a research methodology used to assess the effectiveness of a particular program, policy, or intervention in achieving its intended outcomes. The goal of impact evaluation is to determine whether the desired changes can be attributed to the program or intervention, rather than to external factors. This type of evaluation typically involves comparing outcomes between a group that receives the program or intervention and a control group that does not, in order to measure the causal effect of the intervention. Impact evaluations help to inform decision-making, improve program design, and identify best practices for achieving desired outcomes.