What Is a Meta-Synthesis, and How Is It Different From Meta-Analysis?

Is Meta-Synthesis Simply Meta-Analysis for Qualitative Research?

The names invite the comparison. Meta-analysis combines findings across quantitative studies, while meta-synthesis brings findings across qualitative studies together. It is easy to assume that one is simply the qualitative version of the other.

That comparison is useful only up to a point.

Meta-analysis usually works with numerical estimates that can be combined statistically. Qualitative meta-synthesis works with findings, concepts, interpretations, experiences, and meanings that require interpretive or aggregative synthesis rather than statistical pooling.

The two approaches therefore share a broad objective of generating understanding across multiple studies, but the evidence they synthesize, the questions they answer, and the logic by which they produce new findings are substantially different.

Meta-Analysis Pools Numbers; Meta-Synthesis Integrates Meaning

Why Similar Names Conceal Very Different Forms of Synthesis

Meta-Analysis Is a Statistical Synthesis Method

Meta-analysis combines compatible quantitative results across studies. The studies contribute numerical estimates, such as risk ratios, odds ratios, mean differences, standardized mean differences, correlations, or prevalence estimates, and the analysis combines them using an appropriate statistical model.

The resulting synthesis may provide a pooled effect estimate with a measure of uncertainty. Researchers can also investigate heterogeneity and, when justified, examine potential explanations for variation among study results.

Meta-analysis therefore operates primarily on quantitative estimates. It is one possible component of a systematic review rather than a complete review methodology in itself. As explained in the distinction between meta-analysis and systematic review, a systematic review may contain one, several, or no meta-analyses.

Meta-Synthesis Works With Qualitative Findings

Qualitative research often asks different questions. Researchers may investigate how people experience an intervention, how they interpret an event, why a practice is accepted or resisted, how identities are negotiated, or how social and institutional contexts shape behavior.

When several qualitative studies address related phenomena, reviewers can systematically bring their findings together. The objective is not to calculate an average experience. It is to examine relationships among findings and develop a synthesis that may be more comprehensive, conceptually developed, or transferable than any individual study alone.

This work belongs to the broader family of qualitative evidence synthesis.

Meta-Synthesis Is Not One Universally Defined Method

This is one of the most important terminological cautions. Meta-synthesis does not refer to one universally standardized procedure in the way researchers might expect from the name.

Qualitative evidence synthesis encompasses several methodologies, including meta-ethnography, thematic synthesis, framework synthesis, and meta-aggregation. Different traditions use terms such as qualitative meta-synthesis, qualitative research synthesis, and qualitative evidence synthesis in overlapping ways.

For this reason, saying only "we conducted a meta-synthesis" may leave important methodological questions unanswered. Readers still need to know how studies were identified, what counted as eligible qualitative evidence, how findings were appraised and extracted, and what analytic method was used to develop the synthesis.

Different Qualitative Synthesis Methods Do Different Things

Some qualitative synthesis methods are strongly interpretive. Meta-ethnography, originally developed by Noblit and Hare, involves comparing and translating concepts across studies to develop interpretations that extend beyond individual primary-study accounts.

Other approaches have different objectives. JBI meta-aggregation emphasizes aggregation of findings into categories and synthesized findings intended to support evidence-informed practice. Thematic synthesis develops themes across study findings, while framework synthesis can organize evidence using an existing conceptual framework that may be refined through the synthesis.

These approaches should not be collapsed into one generic procedure simply because all of them work with qualitative research.

You Cannot Create a Qualitative Meta-Analysis by Counting Themes

Suppose 12 of 15 qualitative studies mention lack of time as a barrier, while six mention professional identity. It may be useful to report how findings are distributed across studies, but those counts do not automatically establish that lack of time is twice as important as professional identity.

Qualitative findings differ in richness, context, meaning, and explanatory significance. A theme found in fewer studies may explain an important mechanism or contextual condition that simple frequency counting would miss.

Converting qualitative findings into counts can therefore answer a different question from interpreting their meaning. Frequency information may supplement a synthesis when methodologically appropriate, but it should not replace qualitative analysis merely to make the findings look more quantitative.

Meta-Synthesis Does Not Mean Combining Raw Interview Transcripts From Different Studies

Most published qualitative evidence syntheses work primarily from findings reported in primary research publications rather than obtaining and merging all original interview transcripts or field notes.

The synthesis therefore operates at another analytical level. Participants' accounts have already been interpreted by primary researchers, and review authors subsequently analyze findings or interpretations across those studies.

This layered interpretation is important when evaluating what the synthesis can claim. The reviewer's findings are informed by primary studies, which are themselves interpretations of data generated in particular social and research contexts.

Critical Appraisal Applies to Both, but the Criteria Differ

Both quantitative and qualitative evidence syntheses need to consider limitations in their underlying evidence. The appropriate appraisal questions, however, depend on the research design.

A randomized trial might be assessed for issues such as allocation procedures, missing outcome data, or selective reporting. A qualitative study requires attention to matters appropriate to qualitative inquiry, including congruity among the research methodology, question, data collection, analysis, interpretation, and representation of participants.

Using a quality tool designed for quantitative intervention studies to score qualitative research would therefore be methodologically inappropriate.

Confidence in Qualitative Synthesis Findings Can Still Be Evaluated

Qualitative synthesis does not produce confidence intervals around themes, but researchers can still assess confidence in review findings.

GRADE-CERQual provides an approach for assessing confidence in findings from qualitative evidence syntheses. It considers four components: methodological limitations, coherence, adequacy of data, and relevance.

The resulting assessment concerns how much confidence should be placed in a particular qualitative review finding. It should not be interpreted as a statistical probability or transformed into an effect estimate.

Meta-Analysis and Meta-Synthesis Can Complement Each Other

A research problem may require both quantitative and qualitative evidence.

For example, a meta-analysis might indicate that an educational intervention improves academic performance on average. A qualitative synthesis might reveal that students value the intervention only when feedback is understandable, instructors remain accessible, and the technology does not increase perceived surveillance.

One synthesis estimates what happens across quantitative studies. The other helps explain experiences, implementation, and context. Neither necessarily substitutes for the other.

Two Syntheses Can Examine the Same Intervention From Different Angles

Trying to make one method answer both questions would sacrifice information rather than create a more comprehensive analysis.

Common Misunderstandings About Meta-Synthesis and Meta-Analysis

Let the Question Determine What Kind of Synthesis You Need

Before selecting a synthesis method, complete the sentence: "At the end of this review, I need to understand..." The kind of answer you place after that sentence is often more informative than the methodological label you initially had in mind.

Once you choose qualitative synthesis, specify the actual methodology. "Qualitative evidence synthesis using meta-ethnography" communicates considerably more than simply "meta-synthesis."

Before Choosing Meta-Synthesis or Meta-Analysis

Questions About Meta-Synthesis and Meta-Analysis

One Synthesizes Quantities; the Other Synthesizes Qualitative Meaning

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