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In educational articles aimed at very specialised statistical
issues, the choice of a clear example is a crucial point to help readers
understand the main message conveyed by the paper.
In the article by Sterne et al. , understanding Figure 2 is
essential, but it is unclear why three subgroups of studies (subgroups 1,
2 and 3) are proposed to interpret the results of the meta-analysis taken
as an example, whereas one could think that two subgroups are enough
(subgroups 1 and 2 pooled together vs. subgroup 3).
1. Sterne JAC, Sutton AJ, Ioannidis JPA, et al. Recommendations for
examining and interpreting funnel plot asymmetry in meta-analyses of
randomised controlled trials. BMJ 2011; 343:d4002
No competing interests
23 July 2011
Lab. of Pharmacoeconomics, c/o Area Vasta Centro Toscana, 50100 Firenze, ITALY