A Brief History of Evidence

This article provides a brief history of evidence-based policy, which it defines as encompassing (1) the application of rigorous research methods, particularly randomized controlled trials (RCTs), to build credible evidence about “what works” to improve the human condition; and (2) the use of such evidence to focus public and private resources on effective interventions. Evidence-based policy emerged first in medicine after World War II, and has made tremendous contributions to human health. In social policy, a few RCTs were conducted before 1980, but the number grew rapidly in U.S. welfare and employment programs during the 1980s and 1990s and had an important impact on government policy. Since 2000, evidence-based policy has seen a major expansion in other social policy areas, including education and international development assistance. A recent milestone is the U.S. enactment of “tiered evidence” social programs in which rigorous evidence is the defining principle in awarding government funding for interventions