A little-known perspective on the I-squared statistic
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Updated: Nov 4, 2026

A Psychophysics Paradigm for the Collection and Analysis of Similarity Judgments
Published on: March 1, 2022
Dan Jackson1, Julian P T Higgins2, José Antonio López-López3,4
1AstraZeneca UK Ltd, UK.
Abstract:
The I-squared statistic has become hugely popular in meta-analysis. Motivated by the recent statement that 'Informally, it can be considered to reflect the extent to which confidence intervals displayed in a forest plot do not overlap with each other', this short note formalises this perspective. The insights provided by our analysis lend further weight to the interpretation of the I-squared statistic as a measure of inconsistency. This perspective reminds us that visual inspections of forest plots are vitally important when assessing between-study variation.
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