Organizations face many challenges in measuring their impact using rigorous evaluation methodologies such as randomized controlled trials (RCTs). While technical requirements—such as sufficient sample size—are often an issue, for most organizations the main challenge is overcoming internal and external resistance to impact evaluation.

Some objections are well placed. For example, most operational learning does not require impact evaluation. And for some organizations, a focus on measuring impact may not be appropriate, particularly when it takes resources away from other strategic priorities and program monitoring. External pressures from donors or other stakeholders can be the driving force behind impact evaluations, with both positive and negative consequences. When there is little regard for accuracy or quality, organizations waste resources that could have helped to improve their programs.