I am currently deciding whether to use the Wilcoxon rank test vs two-samples T-test to assess BMI between two unrelated groups. Using the following code to assess normality with(group1, shapiro.test(BMI)) , I got p > 0.05 for group 1 (n = 8) but p < 0.05 for group 2 (n = 20).
I want to know whether this means I should use a non-parametric test for my analysis? I know if both are p < 0.05, then I should definitely use the Wilcoxon rank test BUT I have no clue what to do when only one group is non-normally distributed.