I would like to ask the following: I have two groups (patients, controls). I used the mean and SD of the control group to calculate z-scores from their results on a variety of tests. , both for controls and patients' group. Then, I formed composite z-scores, adding different variables into one (using their z-scores) divided by the number of the variables used to form each composite z-score. Now I would like to ask if it is possible to use an independent samples t-test in order to test differences between the two groups in each variable (z-scores) separately and the composite z-scores as well. Thank you.