Ongoing debate specific to the power properties of the independent samples t test and Wilcoxon Mann-Whitney required a need for this study. Researchers chose the t test over the Wilcoxon, when testing for shift, claiming that in small treatment conditions, the Wilcoxon was erroneously rejecting the null hypothesis due to scale change. Therefore, the purpose of this study was to assess if, in the presence of a slight scale change, the reason the t test fails to reject and the Wilcoxon does reject is due to the scale change and not shift in location. ^ Applying Monte Carlo techniques, the comparative power and robustness of the t test and the Wilcoxon were investigated. In addition to the Gaussian distribution, two real prototypical data sets Smooth Symmetric and Extreme Asymmetry, Achievement, (Micceri, 1989) were applied. Sample Sizes included: (n1, n2) = (10, 30), (30, 10), (20, 20), (15, 45), (45, 15) and (30, 30). The ratio of variance for group one and group two ranged from 1.0-1.2 (increase in increments of .05). Shift/change in location parameters increased from 0.0-1.1 (increments of .05). Nominal alpha was set at .05. ^ Outcomes compared the robustness and power of each test. Recognized as the Behrens-Fisher problem, scale change without change in location, outcomes confirm neither test as robust. In studying shift while holding variance constant; the power of both tests are comparable specific to the Gaussian and Smooth Symmetric distributions, however with extreme skew, the Wilcoxon maintains much greater power. ^ The primary focus of this research is slight change in location and scale change. Under normality, the t test rejects more than the Wilcoxon. Further, as the variance difference increases, both test's rejection rates increase. With the introduction of non-normality, both tests reject at a higher rate, with the Wilcoxon rejecting more frequently then the t test. The outcomes of this study confirm the strength of the t test under normality however when the treatment impacts location, researchers can maintain confidence that if the Wilcoxon rejects the null and the t test does not, this rejection reflects a shift in location. ^