Fig. 8

Heterogeneity and publication bias. (a) Funnel plot illustrating the publication bias and the systematic heterogeneity of the included studies; (b) L’Abbe plot illustrating the heterogeneity of the included studies; (c) Galbraith plot illustrating the contribution of individual studies to the heterogeneity metrics and identify outliers; (d) Baujat plot depicting the contribution of individual studies to overall heterogeneity