Glossary

Effect size

In one lineHow big the difference was, not whether it was statistically significant.

Definition

The magnitude of the difference between groups — kilograms lost, points on a pain scale, percentage change — as opposed to whether the difference reached statistical significance. A trial can be significant and trivial at the same time. LYO shows effect size separately from the evidence grade for exactly that reason.

Definitions are written for a general reader and reviewed with the rest of the site. Not medical advice. Suggest a correction →