Table 2.

Moderator effects.

Potential moderator	F-test	p	Effect size	n	95% CI
Average effect size from individual studies			0.65	52	[0.42; 0.89]
Gender	F(1, 50) = −0.169	ns
Female only			0.63	14	[0.43; 0.84]
Male only			0.66	38	[0.32; 1.00]
Mean age	F(2, 49) = 2.306	ns
<15 years			0.48	8	[0.17; 0.78]
15–20 years			0.88	29	[0.60; 1.15]
>20 years			0.25	15	[−0.45; 0.96]
Sample size	F(2, 49) = 0.304	ns
<20			0.64	17	[0.49; 1.21]
20–30			0.85	18	[0.49; 1.21]
>30			0.50	17	[−0.03; 1.31]
Length of intervention	F(2, 49) = 0.264	ns
Less than 2 weeks			0.31	2	[−0.97; 1.60]
2 to 20 weeks			0.69	32	[0.31; 1.06]
20 weeks and above			0.62	18	[0.43; 0.82]
Skill level	F(2, 49) = 3.315	<0.05
High School			0.77	16	[0.59; 0.95]
Intercollegiate			1.13	16	[0.53; 1.72]
Professional club			0.40	20	[−0.02; 0.83]