We run a study, comparing 3 treatment groups (same 6 individuals), and we are comparing the mean blood flow (in an area) between them. The data is not normally distributed. Would you perform a Friedman and then if there is a difference analyze it with a Mann Whitney U? Do you have to apply a Bonferroni correction here? Because you are comparing means of one variable between 3 groups.. or given that just one variable between the 3 groups is analyzed, we don't need a Bonferroni?