People use the term synthesis in evidence-based practice, policy, research and writing environments. It is a concept and method of combining information together to create something new. That new product could be a personal opinion, an argument for or against implementing a law, policy or clinical practice or could be a step taken when critically appraising or analyzing data from multiple studies as part of the conduct of a systematic review study. Therefore, context when talking about synthesis is very important. Let's review some examples of different definitions of synthesis:
Synthesis as defined in an English dictionary: "The process of combining objects or ideas into a complex whole".
- Collins English Dictionary (https://www.collinsdictionary.com/dictionary/english/synthesis)
Synthesis as defined in its application in writing assignments, research papers, publications:
"Synthesis is where you take multiple pieces of evidence or multiple sources and their ideas and you talk about the connections between those ideas or those sources."
- Analyzing & Synthesizing Sources: Synthesis: Definition and Examples (https://academicguides.waldenu.edu/c.php?g=465757&p=4066126).
Evidence Synthesis as defined as a step and method used appraising and analyzing data in systematic reviews:
“The term synthesis is used to refer to the stage of a review when the evidence extracted from the individual sources is brought together in some way. This may entail simply juxtaposing findings from different sources or identifying and extracting common themes across sources or integrating data from several sources to produce new insights or theories.”
– Mays N, Pope C, & Popay J. (2005). Systematically reviewing qualitative and quantitative evidence to inform management and policy-making in the health field. Journal of Health Services Research & Policy, 10, S1:6-S1:20. Retrieved from https://journals.sagepub.com/doi/pdf/10.1258/1355819054308576
Some researchers define evidence synthesis synonymously with systematic review. However, it is also the specific step in systematic reviews where you take appraised data or studies and combine them and their findings to analyze data to determine if there is enough evidence in the selected studies to develop a conclusive statement about the combined studies in answering a clinical or policy question.