Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
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?

PubMed Disclaimer

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
See this image and copyright information in PMC

Comment in

References

    1. Egger M, Davey Smith G. Meta-analysis: potentials and promise. BMJ 1997;315: 1371-4. - PMC - PubMed
    1. Liberati A, Buzzetti R, Grilli R, Magrini N, Minozzi S. Which guidelines can we trust? West J Med 2001;174: 262-5. - PMC - PubMed
    1. Harbour R, Miller J for the Scottish Intercollegiate Guidelines Network Grading Review Group. A new system for grading recommendations in evidence based guidelines. BMJ 2001;323: 334-6. - PMC - PubMed
    1. Guyatt G, Sinclair J, Cook D, Jaeschke R, Schünemann H, Pauker S. Moving from evidence to action. In: Guyatt G, Rennie D, eds. Users' guides to the medical literature: a manual for evidence-based clinical practice. Chicago: American Medical Association, 2002: 599-608.
    1. Petitti DB. Approaches to heterogeneity in meta-analysis. Stat Med 2001;20: 3625-33. - PubMed

Publication types

MeSH terms