Table 3 Actual significance levels for t-test and MW test relative to nominal α = 0.05: using general population data (females aged 16–45) for the GH and RP dimensions [10]

From: Sample size and power estimation for studies with health related quality of life outcomes: a comparison of four methods using the SF-36

Sample sizes	GH dimension		RP Dimension
	t-test	MW test	t-test	MW test
300, 300	0.0511	0.0490	0.0504	0.0495
250, 250	0.0520	0.0535	0.0497	0.0516
200, 200	0.0543	0.0484	0.0508	0.0521
150, 150	0.0514	0.0527	0.0507	0.0510
100, 100	0.0502	0.0515	0.0518	0.0534
75, 75	0.0493	0.0515	0.0535	0.0500
50, 50	0.0506	0.0522	0.0476	0.0512
25, 25	0.0490	0.0492	0.0526	0.0478
10, 10	0.0428	0.0464	0.0393	0.0456

α = 0.05 (two-sided); 10,000 bootstrap replications.

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