Impact evaluations represent a branch of evaluation methods that in recent years have gained widespread acceptance and been advocated for by key agencies such as the World Bank and the UN. The strength of impact evaluations are largely their ability to determine a causal relationship between a specific program and its intended outcomes. This allows for addressing transparency, accountability and lesson learning; all which are of key interest to stakeholders.
Where sample sizes are large enough and detailed data is available, the question of whom among the participants benefits more and whom that benefits less can be addressed. Impact evaluations can also be used to perform cost-effectiveness analysis that allow for comparison of which of several program alternatives achieves intended outcomes at the lowest cost.