Extensions of the Kruskal-Wallis procedure for a factorial design are examined under various degrees and kinds of nonnullity. It was found that the distributions of these test statistics are a function of effects other than those being tested, except under the completely null situation. Their use is discouraged. (Author/JKS)

Various cases of unequal variances and unequal sample sizes from a normal and a skewed population were used to empirically obtain the probability of a Type I error and the power for the permutation t-test as compared to Student's t-test and the Mann-Whitney U-test. Empirical results showed differences for different sample sizes, variance ratios,…

Compared the analysis of variance (ANOVA) "F" and several nonparametric competitors for two-way designs for empirical alpha and power through simulation. Results suggest the ANOVA "F" suffers from conservative alpha and power for the mixed normal distribution, but is generally recommended. (Author/SLD)

Researchers are often in a dilemma as to whether parametric or nonparametric procedures should be cited when assumptions of the parametric methods are thought to be violated. Therefore, the Kruskal-Wallis test and the ANOVA F-test were empirically compared in terms of probability of a Type I error and power under various patterns of mean…