Table 3.

Heterogeneity of studies

Model	Effect size and 95% interval			Test of null (2-tail)		Heterogeneity				Tau-squared
	Point estimate	Lower limit	Upper limit	Z-value	P-value	Q-value	df (Q)	P-value	I-squared	Tau squared	Standard error	Variance	Tau
Fixed	0.041	0.057	0.040	− 1333.61	0.000	25,612.613	51	0.000	99.801	0.211	0.181	0.033	0.460
Random	0.047	0.042	0.053	− 45.900	0.000