Evidence-appraisal glossary
Trim and Fill
Trim and fill is a method that estimates how many studies may be missing from an asymmetric funnel plot, then imputes them to gauge how much publication bias might have shifted the pooled result. It is a sensitivity check, not a correction of the truth.
Also called: trim-and-fill method, Duval and Tweedie method.
The method trims the apparently asymmetric small studies, re-estimates the center of the funnel, then fills in mirror-image studies to restore symmetry and recomputes the pooled effect. If the adjusted estimate stays close to the original, the conclusion looks robust to missing studies; if it moves substantially, the finding may be fragile. Its imputed studies are hypothetical, and it performs poorly when between-study variability is high, so it informs judgment rather than replacing it.
Read the full Reading the Evidence blog.
This is a plain-language methodology definition for reading research. It is general education, not medical advice.