ROBUSTNESS OF THE 2-SAMPLE T-TEST UNDER VIOLATIONS OF THE HOMOGENEITY OF VARIANCE ASSUMPTION .2.

In a previous paper, Posten, Yeh and Owen (1982), the robustness of the type I error for the two-tailed two-sample t-test was studied under departures from the assumption of equal variances. The level of robustness of this test was then quantified under the concept of regions of robustness. These results are extended here to the one-tailed test for the same problem. The high level of robustness for equal or nearly equal sample sizes observed in the previous study is again documented quantitatively.