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Program Evaluation: Key Terms and Concepts

GAO-21-404SP Published: Mar 22, 2021. Publicly Released: Mar 22, 2021.
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Congress has passed a number of laws to help improve federal management and accountability—including the GPRA Modernization Act of 2010 and the Evidence Act of 2018. These acts aim to strengthen agencies' efforts to build strong evidence to support federal policies.

We developed this glossary to clarify some key concepts that can help federal agencies strengthen the quality of their evidence. It highlights different sources of evidence that can support federal decision-making—such as program evaluations and performance measurement.

This is an update to our previous glossary (GAO-11-646SP).

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Both the executive branch and congressional committees need evaluative information to help them make decisions about the programs they oversee—information that tells them whether, and why, a program is working well or not. The Government Performance and Results Act of 1993 (GPRA) and GPRA Modernization Act of 2010 (GPRAMA) established a framework for performance management and accountability within the federal government. Building on that foundation, Congress has since passed, among other laws, the Foundations for Evidence-Based Policymaking Act of 2018 (Evidence Act) to strengthen the evidence-building efforts of executive branch agencies. This product updates our previous glossary (GAO-11-646SP) to highlight different types of evaluations for answering questions about program performance, as well as relevant issues to ensure study quality. This glossary can help agency officials better understand fundamental concepts related to evaluation and enhance their evidence-building capacity.

For more information, contact Lawrance Evans, Jr. at 202-512-2700 or

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