Fig. 4

Distribution curve of the true effect size, assuming a normal distribution of effects (on a log scale). The plot illustrates the pooled odds ratio (OR), its 95% confidence interval (CI), and the prediction interval, which ranges from 0.319 to 3.354. This interval represents the range in which the true effect size is expected to fall in 95% of comparable populations. The central point reflects the pooled OR, while the thick horizontal line indicates the 95% CI. The extended horizontal line represents the prediction interval, accounting for between-study heterogeneity