Summary: Data synthesis
- Synthesis involves bringing the results of individual studies together and summarising their findings.
- This may be done quantitatively or, if formal pooling of results is inappropriate, through a narrative approach.
- Synthesis should also explore whether observed intervention effects are consistent across studies, and investigate possible reasons for any inconsistencies.
Initial descriptive synthesis
All syntheses should begin by constructing a clear descriptive summary of the included studies.
Narrative synthesis is frequently an essential part of a systematic review, and as with every other stage of the process, bias must be minimized. Narrative synthesis has typically not followed a strict set of rules. However, a general framework can be applied in order to help maintain transparency and add credibility to the process. The four elements of this framework are:
- Developing a theory of how the intervention works, why and for whom
- Developing a preliminary synthesis of findings of included studies
- Exploring relationships within and between studies
- Assessing the robustness of the synthesis
Each element contains a range of tools and techniques that can be applied. A researcher is likely to move iteratively among the four elements, choosing those tools and techniques that are appropriate to the data being synthesised and providing justifications for these choices.
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