Fig. 6

Funnel plot for publication bias. This funnel plot visually assesses the potential presence of publication bias in the included studies. The plot represents study effect sizes on the x-axis and their corresponding standard errors on the y-axis. In an ideal scenario without bias, the studies should be symmetrically distributed around the combined effect size estimate. The figure shows the distribution of studies, with any asymmetry potentially suggesting publication bias, where studies with significant findings are more likely to be published than those with null results