Evidence Synthesis Methodologies
Synthesis methodologies vary across disciplines, both in name and in practice. These variations often reflect the unique needs, standards, and challenges of research fields. Despite their differences, the goal of these methods is focused on ensuring systematic and transparent processes. This guide focuses on the two primary methods of evidence synthesis used within conservation and environmental sciences, Systematic Reviews and Systematic Maps.
| Systematic Reviews | Systematic Maps | |
|---|---|---|
| Objective |
Support evidence-based decision-making, policy, and practice by assessing and integrating available evidence to answer a specific research question. Strengthen the reliability and validity of findings by ensuring a rigorous and transparent process to discover, screen, appraise, and combine study findings. |
Support strategic decision-making and guide future research by providing an overview of the existing evidence based on a research topic or question. Improve the understanding of the evidence landscape by mapping knowledge gaps, emerging trends, and clusters of evidence that offer opportunities for further synthesis to support policy and decision-making. |
| Scope | Typically addresses a closed-framed question with well-defined populations, interventions, comparators, and outcomes. | Often addresses a broader, open-framed question that may not be suitable for a systematic review due to multiple populations, interventions, or outcomes. |
| Critical Appraisal of Studies | Mandatory. Assesses the risk of bias and external validity of included studies to determine the reliability and applicability of findings. | Optional. May assess study validity if relevant indicators can be coded, but this doesn't influence the mapping process itself and is not common. |
| Synthesis | Can employ quantitative and/or qualitative synthesis, aiming to provide an answer to the research question. Can use meta-analysis to statistically combine findings from multiple studies. | Employs visual/graphical synthesis, focusing on describing and categorizing the evidence base. Maps use data visualizations (e.g., tables, maps, graphs) to present the distribution and abundance of evidence across key elements of the research question. |
| Output | A quantitative or qualitative answer to the research question with an indication of uncertainty and potential sources of bias. May include an estimate of the magnitude and direction of an effect. | A visual and descriptive overview of the evidence base, highlighting the distribution and abundance of evidence across different study designs, populations, interventions, outcomes, and other key elements. May include an interactive database of studies. |
