Studies

VR^a Mean (S.D.)

Control Mean (S.D.)

Mean difference (95% CI)

Zhao 2011a [7]

2.79 (0.79)

1.98 (1.12)

0.81 (−0.04 to 1.66)

Zhao 2011b [8]

3.48 (1.87)

2.64 (1.46)

0.84 (−0.63 to 2.31)