A professor of women's studies is interested in determining if stress decreases skin clarity ...

     A   professor of women's studies is interested in determining if stress decreases   skin clarity. Ten students are randomly divided into two groups. One of the   groups is subjected to high stress for 1 month while the other lives   relatively stress free. Below are the measured number of pimples on each   person's face during the month. No stress: 20 23 18 19 22 High stress: 26 31   25 26 30 Conduct null hypothesis test (which one is used). Determine if you   have violated the assumption of homogeneity of variance.