(b).

Number	First author	Statistics for each study					Difference in means and 95% CI	Relative weight
		Difference in means	Standard error	Variance	Z value	P value
7 10	Henderson (2007) [14] Henderson (2005) [7] Total	−1.400 −2.900 −2.342	1.335 1.027 0.814	1.783 1.055 0.663	−1.048 −2.823 −0.747	0.294 0.005 0.004		37.18 62.82 100.00

Heterogeneity: Q = 0.79; df = 1; P = 0.37; I ² = 0.00.