International development programs are designed to achieve important improvements in health, education, and financial well-being for disadvantaged populations (e.g., reduced maternal and child mortality; increased farmer crop yields; or improved primary education enrollment rates). Despite these intentions, many development programs do not measure whether they ultimately achieve their desired results because the outcomes can be challenging to measure, and may occur well into the future. As a result, we often miss out on opportunities to learn about the most effective and efficient uses of scarce development resources. An impact evaluation measures program effectiveness by comparing the outcomes of those who received a program against those who did not. By establishing a valid counterfactual, or an estimate of what an outcome would be in absence of the program, impact evaluations can credibly measure and attribute any changes in outcomes between participants and nonparticipants to the program. With this information, decision-makers can make more informed choices about which programs to support and how to improve them.
A long-term impact evaluation (LTIE) measures outcomes over longer time horizons than a typical impact evaluation. LTIEs typically occur after program implementation is complete, and address questions about a program’s impact that cannot be answered within the span of a typical evaluation or program life cycle. They can provide crucial information on whether observed outcomes are sustained over time, allowing the United States Agency for International Development (USAID) and others to make long-term strategic management and funding decisions, particularly in sectors with theories of change with critical outcomes materializing well after a program ends.