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Systematic Reviews

Specialised advice for planning, researching and writing Systematic Reviews.


Synthesis is a stage in the review process where extracted data are pooled together and evaluated.


It is one of the most important stages of the review process, as it determines the outcomes of the review.


The synthesis stage includes:

  • A narrative synthesis which combines and connects the findings of the individual studies and identifies relationships between them.
  • A narrative analysis of the strength of evidence such as the quality of the sources and risk of bias assessments.
  • A synthesis of quantitative data via a meta-analysis (if applicable) and/or narrative analysis. Meta-analyses often also include aspects of qualitative data synthesis to explain why studies have been excluded or differ from the findings of the meta-analysis.

Quantitative data synthesis

In a quantitative systematic review, which explores similar studies, data can be processed as a narrative describing the different findings or can be processed through a meta-analysis if the data is comparable.

During meta-analysis, data from different studies are weighted depending on their sample size and relevant criteria, and evaluated to determine the cumulative outcome.

Please see the Meta-analysis guide for more information.

Qualitative data synthesis

In a qualitative systematic review, data will be synthesised by comprehensive critical appraisal through either a meta-study or a meta-synthesis.

  • A meta-study is a specific research approach in which the theory, methods and findings of qualitative research are analysed and synthesised to develop new ways of thinking about a topic.
  • A meta-synthesis uses interpretive methods to synthesise the findings from primary studies, which can often vary in important respects (such as populations or settings), to produce new insights and understandings.

Neither of these methods involves the reanalysis of raw data from the primary qualitative studies.

Both meta-studies and meta-syntheses can be used to determine what is known and what is not known, reflect on the processes and perspectives of the relevant body of research, explore the underlying methodological decisions and theoretical influences, and suggest future directions for researchers, theoreticians and clinicians.

Adapted from the Monash University Systematic Review libguide.

Forest Plots

For a meta analysis, producing a forest plot may be necessary.

Synthesis tools

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