Figure 4.

Box plots of fold changes of overall proportion estimates produced by various meta-analysis methods compared with those by the generalized linear mixed model with the logit link among Cochrane datasets, categorized by the total event count within a meta-analysis. Because many datasets led to extreme values of fold changes, the box plots do not present outliers, and the vertical axis only presents the range from 1 to 2. The two-step method (DAS-H, DAS-G, DAS-A, or DAS-IV) corresponds to the Freeman–Tukey double-arcsine (DAS) transformation, using the harmonic (H), geometric (G), or arithmetic (A) mean of study-specific sample sizes, or using the inverse of the variance (IV) of the synthesized result, as the overall sample size.