I am in the process of checking the assumptions of some data in order to perform a T-Test and had a few questions about how they should be set up. I was able to find the assumptions for a T-test here.
I have one independent variable with two nominal groups, A and B and one dependent variable that is an interval variable as rank does matter.
For the last three assumptions, i.e. Assumption of no outliers, Assumption of Normality, and Assumption of Homogeneity of Variances, should I test each assumption against each independent's group of values? As in test group A for outliers and normality, as well as test group B's outliers and normality?
The reason for my question is because the Normality Assumption is the only one that requires the user to test each independent's group. You cannot check for Homogeneity of Variances of one group as that produces an error.
Should I check group A only for outlier's and normality or should I only test the values of the dependent variable?