# Should I use Wilcoxon Signed Rank or Mann Whitney U in this question?

Stats newbie here currently trying to teach myself some stats topics. When testing for evidence that mean earnings per share were higher in 1988, should I use Wilcoxon Signed Rank since the samples can be paired?

But I'm still confused about the different uses of tests. What changes in the details of the problem would be required for me to be able to use Mann Whitney U, a t-test, and a z-test?

Thank you!

• 1. Your initial question is a self-study question. You should the self-study tag, read its tag wiki and follow the guidelines there (which you partly do already but you should explain your thoughts/understanding of the question in more detail if possible). On that question -- it's not that the samples can be paired -- they are paired. That should not be ignored. $\:$ 2. The question at the end is not a self-study question and should be asked separately. – Glen_b -Reinstate Monica Apr 22 '16 at 11:18