Evidence-appraisal glossary
Random-effects model
A random-effects meta-analysis assumes the true effect varies from study to study and estimates the average of a distribution of effects rather than a single value. It gives relatively more weight to smaller studies than a fixed-effect model does.
Also called: random effects model, random-effects meta-analysis.
It is chosen when clinical or methodological differences make one common effect implausible, and it produces wider confidence intervals that reflect the between-study variance (tau-squared). The caveat is that it accounts for heterogeneity rather than removing it: with only a few studies the between-study variance is estimated poorly, and the pooled average may not describe any particular patient or setting.
This is a plain-language methodology definition for reading research. It is general education, not medical advice.