Safety and research
Definition
A meta-analysis is a statistical synthesis that combines compatible effect estimates from two or more studies.
Aliases and abbreviations
statistical evidence synthesis · pooled analysis
Editorial record
Published: August 25, 2026 · Reviewed: August 25, 2026
Expanded definition
Meta-analysis can improve precision and show the direction and spread of results across studies, but the pooling model and included data must match a clearly defined question.
The summary estimate inherits the limitations of the studies and the review process. Risk of bias, indirectness, imprecision, heterogeneity, and missing results can make a precise-looking number misleading.
Pooling is not always appropriate. If interventions, populations, comparators, outcomes, or follow-up periods differ substantially, separate analyses or narrative synthesis may be more responsible.
What the term does not establish
Why the distinction matters
Readers need to interpret the pooled number together with study compatibility, uncertainty, and certainty of evidence.
Main guide
Evidence summaries include systematic reviews and meta-analyses relevant to VNS, HRV, safety, and sleep.
Browse evidence synthesesSources and further reading
Related terms
Safety and research
Safety and research
Measurement and interpretation
Measurement and interpretation
Safety and research
Safety and research
Editorial scope
This glossary entry supports general education. It does not diagnose, recommend treatment, or transfer findings from one VNS method, protocol, or device to another.