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arXiv · 1410.2296

Estimates of heterogeneity (I2) can be biased in small meta-analyses

Paul T. von Hippel
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Abstract

In meta-analysis, the fraction of variance that is due to heterogeneity is known as I2. We show that the usual estimator of I2 is biased. The bias is largest when a meta-analysis has few studies and little heterogeneity. For example, with 7 studies and the true value of I2 at 0, the average estimate of I2 is .124. Estimates of I2 should be interpreted cautiously when the meta-analysis is small and the null hypothesis of homogeneity (I2=0) has not been rejected. In small meta-analyses, confidence intervals may be preferable to point estimates for I2.

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Paul T. von Hippel. 2014-10-10. Estimates of heterogeneity (I2) can be biased in small meta-analyses. https://doi.org/10.1186/s12874-015-0024-z

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