Effectiveness is one of five evaluation criteria used by the Organisation of Economic Development Cooperation (OECD). The other four are coherence, efficiency, sustainability, relevance, and impact. The OECD Development Assistance Committee Network on Development Evaluation defines effectiveness as “the extent to which the intervention achieved, or is expected to achieve, its objectives, and its results, including any differential results across groups.”. In simpler terms, the main question under effectiveness is “is the intervention achieving its objectives?”.
Definition adapted from OECD/DAC Network on Development Evaluation (2019):“Better Criteria for Better Evaluations. Revised Evaluation Criteria. Definitions and Principles for Use”.