I have two groups of each gender and I need to compare two sets of scores for one gender each (a and b class for gender 0 & c and d class for gender 1). In comparing these scores, I am looking for the differences between the two scores with a large sample size (~50 samples). My question is should I be attempting to use a nonparametric method (like that of a WIlcoxon ranked sum test) or a parametric method (like that of a T-test). T-test shows the difference of the means as evident from the output file I ran, while Wilcoxon Ranked sum seems to give me variable data on the Wilcoxon scores for each class. Any help would be appreciated.
P