CONTRACT OEC-5-10-154

The area investigated in the present study is the comparison of the permutation t-test with Student's t-test and the Mann-Whitney U-test. The comparison was made for small samples for three distributions, including a normal distribution, a uniform distribution, and a skewed distribution. The properties of each test compared were the probability of a Type I error and the power against a location-shift alternative hypothesis. The present research indicates that the permutation t-test is an acceptable statistical procedure for the two-sample problem for the normal and uniform populations and suggests that it might be more desirable than the traditional Student's t-test when sample sizes are proportional to the means and the parent population is nonnormal and asymmetric. Further research is needed before a more definite statement can be made about the permutation t-test when sampling from nonnormal populations. (Author