What Do We Mean by "Evidence"?

Practice Matters, April 2014

A publication of the Act for Youth Center of Excellence


by Mary Maley

About the Author

Mary Maley is an extension associate with the ACT for Youth Center of Excellence and directs the Research Synthesis Project at the Bronfenbrenner Center for Translational Research, Cornell University.


The increased use of evidence in public health decision making has created renewed focus on what the term "evidence" means. In this article, we briefly consider what constitutes evidence, as well as how the types of evidence come together to support decision making.

What is Evidence?

There are many types of evidence:

Standards for Evidence

Standards for evidence vary according to the context in which the research is being conducted and the ability to employ a rigorous study design. The highest quality evidence is characterized by well-designed empirical studies or systematic review of all of the studies investigating a given research question. For example, many prevention programs have incorporated research evidence into practice with the use of Evidence-Based Programs, which have been found to be effective based on the results of peer-reviewed evaluations, typically using randomized control trials or quasi-experimental designs (Cooney et al., 2007). RCTs are often considered the gold standard, but these studies can be expensive, lengthy, and/or not ethically feasible, putting this methodology beyond the reach of many researchers. When RCTs are not available, practitioners and policy makers must evaluate the available evidence to guide decision making.

Criteria for Evaluating Evidence

We can evaluate evidence by looking into its quality, the expertise of investigators and reviewers, and its relevance to the question at hand:

Evidence-based Decision Making

Evidence-based decision making is the integration of the best available research evidence with the best available practice-based evidence, including both experiential and contextual evidence, to identify the most appropriate strategies for implementation (Puddy & Wilkins, 2011).

Glossary of Research Studies