I would like to analyze data on questionnaire scores on quality of life between two different groups. There are 20 quality of life questions, all with responses on a Likert scale 1-7. So I have an overall score out of 140 for each person and 20 individual scores out of 7. There are 100 individuals in group 1 and 50 in group 2.
My plan is to first perform a non-parametric Mann Whitney test to compare the overall score between the 2 groups.
I could then perform a linear regression on overall score, and/or ordinal logistic regression for each question; Y= Score(1-7) & X= control/case, but then I would have 20 models.
My question is whether I should be considering multivariate analysis in this case?