I have pre- and post- treatment survey responses measured on an ordinal scale (1-5). There are two treatment groups (control and intervention). I understand if I want to test whether there is a difference in the before and after response I will need to use the Wilcoxon-signed rank test - i.e. the non-parametric alternative to the paired t-test (performed for each group).
But what if I also want to test if the before and after difference in response is different between groups?
My thought here was then to compare the pre-post difference between groups using the Mann-Whitney U test (non-parametric alternative to the independent samples t-test).
Is this correct?