定義一 / Definition 1

針對干預措施（或活動）如何影響成果所做的一項評估，無論這些效果是刻意達到還是非預期出現的。對影響力的適當分析需要反事實的資訊，即這些成果在沒有干預活動出現下的情況。
An assessment of how the intervention (or activities) being evaluated affects outcomes, whether these effects are intended or unintended. The proper analysis of impact requires a counterfactual of what those outcomes would have been in the absence of the intervention.

出處 / Source
OUTLINE OF PRINCIPLES OF IMPACT EVALUATION (2006) OECD https://www.oecd.org/development/evaluation/dcdndep/37671602.pdf

定義二 / Definition 2

由獨立的第三方評估人員進行影響力評估是適當的，特別是在利害關係人面臨高風險和/或不容易逆轉的情況下。
Impact evaluations carried out by independent third-party evaluators may be appropriate, especially where the risks to Stakeholders are high and/or not easily reversed.

出處 / Source
United Nations Development Programme. (2021). SDG Impact Standards Glossary. https://sdgimpact.undp.org/assets/SDG-Impact-Standards-Glossary.pdf