Measurement and interpretation
Definition
Certainty of evidence expresses how confident reviewers are that the true effect is close to the reported estimate for a specific outcome.
Aliases and abbreviations
confidence in the evidence · quality of evidence · GRADE certainty
Editorial record
Published: August 25, 2026 · Reviewed: August 25, 2026
Expanded definition
Using GRADE, a body of evidence is commonly rated high, moderate, low, or very low for a defined outcome and comparison.
Reviewers consider domains such as risk of bias, inconsistency, indirectness, imprecision, and publication or non-reporting bias. The judgement applies to the body of evidence, not to a topic in the abstract.
Certainty is separate from effect size and statistical significance. A large or significant estimate may still have low certainty, while a small precise estimate may have high certainty.
What the term does not establish
Why the distinction matters
Certainty helps readers distinguish what the evidence estimates from how much confidence should be placed in that estimate.
Main guide
An evidence map that separates mechanisms, outcomes, method families, and confidence boundaries.
Explore evidence boundariesSources and further reading
Related terms
Safety and research
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Measurement and interpretation
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Measurement and interpretation
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.