Table 2.

Meta regression analysis for the included studies to identify source of heterogeneity

Covariate (source)	Coefficient	Standard error	P-value	95% Conf. Interval
Publication year	−0.416	0.530	0.442	− 1.526, 0.694
Sample size	0.0002	0.001	0.869	−0.003, 0.0035