Table 5 Estimated probabilities (%) that the p-value of the WMW test is smaller than that of the t-test, averaged over 32 combinations of amount of skewness and standard deviation ratios
From: t-tests, non-parametric tests, and large studies—a paradox of statistical practice?
Number of subjects in each group | |||||||
|---|---|---|---|---|---|---|---|
10 | 25 | 50 | 100 | 250 | 500 | 1000 | |
Gamma distributions | 54.1 | 63.3 | 69.8 | 75.8 | 82.6 | 86.8 | 90.3 |
Lognormal distributions | 45.6 | 52.1 | 56.9 | 62.3 | 70.1 | 76.3 | 82.5 |