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Updated tests for small-study effects in meta-analyses


  • Roger M. Harbord

    () (University of Bristol)

  • Ross J. Harris

    () (Health Protection Agency, UK)

  • Jonathan A. C. Sterne

    (University of Bristol)


This article describes an updated version of the metabias command, which provides statistical tests for funnel plot asymmetry. In addition to the previously implemented tests, metabias implements two new tests that are recom- mended in the recently updated Cochrane Handbook for Systematic Reviews of Interventions (Higgins and Green 2008). The first new test, proposed by Harbord, Egger, and Sterne (2006, Statistics in Medicine 25: 3443–3457), is a modified ver- sion of the commonly used test proposed by Egger et al. (1997, British Medical Journal 315: 629–634). It regresses Z/√V against √V , where Z is the efficient score and V is Fisher’s information (the variance of Z under the null hypothesis). The second new test is Peters’ test, which is based on a weighted linear regression of the intervention effect estimate on the reciprocal of the sample size. Both of these tests maintain better control of the false-positive rate than the test proposed by Egger at al., while retaining similar power. Copyright 2009 by StataCorp LP.

Suggested Citation

  • Roger M. Harbord & Ross J. Harris & Jonathan A. C. Sterne, 2009. "Updated tests for small-study effects in meta-analyses," Stata Journal, StataCorp LP, vol. 9(2), pages 197-210, June.
  • Handle: RePEc:tsj:stataj:v:9:y:2009:i:2:p:197-210

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    References listed on IDEAS

    1. Thomas J. Steichen & Matthias Egger & Jonathan Sterne, 1999. "Tests for publication bias in meta-analysis," Stata Technical Bulletin, StataCorp LP, vol. 8(44).
    2. Tom M. Palmer & Jaime L. Peters & Alex J. Sutton & Santiago G. Moreno, 2008. "Contour-enhanced funnel plots for meta-analysis," Stata Journal, StataCorp LP, vol. 8(2), pages 242-254, June.
    3. Jonathan A.C. Sterne & Roger M. Harbord, 2004. "Funnel plots in meta-analysis," Stata Journal, StataCorp LP, vol. 4(2), pages 127-141, June.
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    Cited by:

    1. Tseday Jemaneh Mekasha & Finn Tarp, 2013. "Aid and Growth: What Meta-Analysis Reveals," Journal of Development Studies, Taylor & Francis Journals, vol. 49(4), pages 564-583, April.
    2. Sevigny, Eric L. & Fuleihan, Brian K. & Ferdik, Frank V., 2013. "Do drug courts reduce the use of incarceration?: A meta-analysis," Journal of Criminal Justice, Elsevier, vol. 41(6), pages 416-425.
    3. Viechtbauer, Wolfgang, 2010. "Conducting Meta-Analyses in R with the metafor Package," Journal of Statistical Software, Foundation for Open Access Statistics, vol. 36(i03).
    4. Nick Freemantle, 2008. "Biostatistical aspects for the use of evidence based medicine in health technology assessment," The European Journal of Health Economics, Springer;Deutsche Gesellschaft für Gesundheitsökonomie (DGGÖ), vol. 9(1), pages 31-43, November.
    5. Maamar Sebri, 2014. "A meta-analysis of residential water demand studies," Environment, Development and Sustainability: A Multidisciplinary Approach to the Theory and Practice of Sustainable Development, Springer, vol. 16(3), pages 499-520, June.


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