Table 3.

Meta-regression analysis for exploration of the sources of heterogeneity factors

Factors	Coefficient	Standard error	95% CI	p value
year	−0.12	0.20	−3.06, 0.67	0.21
country	−1.19	0.95	−2.99, 0.54	0.17
learners	1.08	1.24	−1.35, 3.52	0.38
course	−0.26	0.89	−2.01, 1.49	0.77
intervention	−0.33	0.79	−0.53, 0.27	0.67
comparator	0.29	0.86	−1.40, 1.99	0.73
duration	0.09	0.95	−1.77, 1.97	0.91