According to Evidence Synthesis International, "Evidence synthesis is the interpretation of individual studies within the context of global knowledge for a given topic. These syntheses provide a rigorous and transparent knowledge base for translating research in decisions. As such, evidence syntheses can be thought of as the basic unit of knowledge used in tools such a policy brief or clinical practice guideline.
In other words, evidence syntheses are the “evidence-base” in evidence-based policy, or evidence-based medicine etc. Essential to all evidence syntheses is the use of explicit and transparent methodology in the formation of the questions they address. The transparent methodology encompasses how studies are identified, selected, appraised, analyzed, and the strength of the evidence assessed to answer the questioned posed."
Evidence Synthesis International. (2019, October 1). About evidence synthesis. – bringing together organizations from around the world to advance methods and teaching of evidence synthesis. https://evidencesynthesis.org/about/about-evidence-synthesis/
The levels of evidence rise in hierarchy based on quality of the research design and as it increases, the risk of bias on each tier decreases.
Golden, Sherita & Bass, Eric. (2013). Validity of meta-analysis in diabetes: Meta-analysis is an indispensable tool in evidence synthesis. Diabetes Care, 36(10), 3368-3373. https://doi.org/10.2337/dc13-1196
Evidence-based practice (EBP) involves using the most up-to-date, accurate evidence available from high quality research and expert experience. In addition, "integrating individual clinical expertise with the best available external clinical evidence from systematic research."
Sackett, D. L., Rosenberg, W. M., Gray, J. A., & Haynes, R. B. (1996). Evidence based medicine: What it is and what is isn't. BMJ, 312(7023). 71-72. https://doi.org/10.1136/bmj.312.7023.71
Here is a visualization of Evidence-Based Practice (EBP) and using Assess, Ask, Acquire, Appraise, Apply:
This graphic was created by Megan York, Education Librarian at the University of Arkansas.