A Bound for Publication Bias Based on the Fraction of Unpublished Studies
Article first published online: 11 MAR 2004
Volume 60, Issue 1, pages 146–153, March 2004
How to Cite
Copas, J. and Jackson, D. (2004), A Bound for Publication Bias Based on the Fraction of Unpublished Studies. Biometrics, 60: 146–153. doi: 10.1111/j.0006-341X.2004.00161.x
- Issue published online: 11 MAR 2004
- Article first published online: 11 MAR 2004
- Received December 2002. Revised June 2003. Accepted July 2003.
- Publication bias
Summary. Publication bias in meta-analysis is usually modeled in terms of an accept/reject selection procedure in which the selected studies are the “published” studies and the rejected studies are the “unpublished” studies. One possible selection mechanism is to suppose that only studies that report an estimated treatment effect exceeding (or falling short of) some threshold are accepted. We show that, with appropriate choice of thresholds, this attains the maximum bias among all selection mechanisms in which the probability of selection increases with study size. It is impossible to estimate the selection mechanism from the observed studies alone: this result leads to a “worst-case” sensitivity analysis for publication bias, which is remarkably easy to implement in practice. The method is illustrated using data on the effectiveness of prophylactic corticosteroids.