Table 4. Subgroup analysis of the form of PERT and the sample size.

	Method	Subgroup	Study	WMD (95% CI)	Z	P	Heterogeneity
							P	I2	Tau2
CFA	Form	Standardization	5	17.86 (13.83, 21.89)	8.68	0.000	0.148	41.1%	7.880
		Non-standardization	2	15.53 (–7.20, 38.25)	1.34	0.181	0.000	94.3%	253.850
	Sample	< 50	4	16.80 (8.42, 25.19)	3.93	0.000	0.000	83.9%	53.870
		> 50	3	19.06 (10.75, 27.37)	4.50	0.000	0.052	66.2%	34.501