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Review
. 2003 Sep 6;327(7414):557-60.
doi: 10.1136/bmj.327.7414.557.

Measuring inconsistency in meta-analyses

Julian P T Higgins  1 , Simon G Thompson, Jonathan J Deeks, Douglas G Altman
Affiliations
Review

Measuring inconsistency in meta-analyses

Julian P T Higgins et al. BMJ. .

Abstract

Cochrane Reviews have recently started including the quantity I2 to help readers assess the consistency of the results of studies in meta-analyses. What does this new quantity mean, and why is assessment of heterogeneity so important to clinical practice?

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Figures

Fig 1
Fig 1
Eight trials of amantadine for prevention of influenza. Outcome is cases of influenza. Summary odds ratios calculated with random effects method
Fig 2
Fig 2
Distribution of observed values of I2 based on odds ratios from 509 meta-analyses of dichotomous outcomes in the Cochrane Database of Systematic Reviews. Data are from the first subgroup (if any) in the first meta-analysis (if any) in each review, if it involved a dichotomous outcome and at least two trials with events. Meta-analyses conducted with metan in STATA
Fig 3
Fig 3
Meta-analyses of six case-control studies relating residential exposure to electromagnetic fields to childhood leukaemia. Summary odds ratio calculated by random effects method
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