An Empirical Investigation of Tukey's Honestly Significant Difference Test with Variance Heterogeneity and Equal Sample Sizes, Utilizing Box's Coefficient of Variance Variation Page: 3

                                
Strozeski, Michael Wayne, An Empirical Investigation
of Tukey's Honestly Significant Difference Test with Variance
Heterogeneity and Equal Sample Sizes, Utilizing Box's
Coefficient of Variance Variation. Doctor of Philosophy
(Educational Research), May, 1980, 1.45 pp., 50 tables, bibli-
ography, 50 titles.
This study sought to determine boundary conditions for
robustness of the Tukey HSD statistic when the assumptions
of homogeneity of variance were violated. Box's coefficient
of variance variation, C , was utilized to index the degree
of variance heterogeneity. Selected numbers of comparison
groups and equal sample sizes were evaluated. Tukey's HSD
statistic was declared robust if the actual significance
level fell within the 95 per cent confidence limits around
the corresponding nominal significance level.
A Monte Carlo computer simulation technique was employed
to generate data under controlled violation of the homogeneity
of variance assumption. For each sample size and number of
treatment groups condition, an analysis of variance F-test
was computed, and Tukey's multiple comparison technique was
calculated. This procedure was repeated 4,000 times; the
actual level of significance was determined and compared to
the nominal significance level of 0.05. The index of vari-
ance variation was systematically adjusted, and this procedure