I have two groups with very small sample sizes (just 6 obs per each group).It seems that There is a violation of normality and Homogeneity of variances (based on Plots).
Now I was wondering if I can use Mann-Whitney test to check the equality of medians although these two group donot have the same shape? Also as levene test doenot have the high power when we have small sample size, I though maybe I should compare the equality of variances based on rule of Thumb, But I am not sure whether the critical value for the rule of Thumb (equality of variances) is 3 or 9?
Any Advice would be highly appreciated.
This is the first analyte (More information: Both P values based on T-test and Mann-Whitney tests are not significant, T-test P value is 0.2 and Mann-Whitney test is 0.5)
This is the second analyte (More information: Both P-values based on T-test and Mann-Whitney tests are very small, around 0.002)