I'm evaluating a survey regarding the opinion. Now I check for relations/similarities inbetween the independent variables. My German workbook names the following condition for a Spearman rank correlation without further explanation:
"At least one variable is ordinal-scaled and/or not normally distributed."
But when I look at how Spearman rank correlation works, there is only sense in using the test if both variables are at least ordinal-scaled. Why does the German workbook tell otherwise? Is there something I am missing?
Now I'm looking for another appropriate test to test relations between the independent variables with the following properties:
- not normally distributed
- variable a: dichotomous or categorical (>2 categories)
- variable b: ordinal scaled or continuous.
I consider Mann Whitney U test and Kruskall-Wallis test. Are there more appropriate tests to identify relations inbetween the independent variables? And can I use the same tests for testing relations between the independent and dependent variables?