Figure 2.

Forest plot for effect sizes of maternal age of birth on externalizing behaviors

SMD = effect size (standardized mean difference)

95%–CI = 95% confidence interval of the effect size

Weight = proportion of the total weight. The total weight refers to the sum of the inverse of the within-study variance for each study plus between-studies variance (τ²). In this graph, the weight assigned to each study is reflected in the size of the box area around effect size)

Random effects = summary effect size (mean of effect sizes from included studies)

I² = ratio of heterogeneity to total observed variance

τ² = between-study variance (variance of effect sizes across included studies)