Monte Carlo methods were used to examine Type I error and power rates of 2 versions (conventional and robust) of the paired and independent-samples t tests under nonnormality. The conventional (robust) versions employed least squares means and variances (trimmed means and Winsorized variances) to test for differences between groups.
Fradette, Katherine; Keselman, H. J.; Lix, Lisa; Algina, James; and Wilcox, Rand R.
"Conventional And Robust Paired And Independent-Samples t Tests: Type I Error And Power Rates,"
Journal of Modern Applied Statistical Methods:
2, Article 22.
Available at: http://digitalcommons.wayne.edu/jmasm/vol2/iss2/22