Studies

VR^a Mean (S.D.)

Control Mean (S.D.)

Mean difference (95% CI)

Zhao 2011a [7]

3.54 (0.82)

2.51 (0.97)

1.03 (0.24 to 1.82)

Zhao 2011b [8]

3.56 (1.79)

2.97 (1.72)

0.59 (−0.95 to 2.13)