is about has_specified_input achieves_planned_objective data transformation trimmed mean study group population between group comparison objective between group comparison statistical test Yuen t-Test with trimmed means 2 Biometrika (1974) 61 (1): 165-170 10.1093/biomet/61.1.165 Philippe Rocca-Serra The Yuen's t-test is a two sample t-test with populations of unequal variance which provides a more robust t-test procedure under normal distribution and long tailed distributions. The test computes a t statistics not using 'arithmetic means' but using 'trimmed means' instead as well as winsorized variances. Yuen-Welch's t-test http://finzi.psych.upenn.edu/library/DescTools/html/YuenTTest.html ready for release