To use the Wilcoxon Rank Sum Test as a test for location, we must assume that
A) the obtained data are either ranks or numerical measurements that will be converted to combined ranks.
B) both samples are randomly and independently drawn from their respective populations.
C) both underlying populations from which the samples were drawn are equivalent in shape and dispersion.
D) All of the above.

Question

Quizplus · Accepted Answer

A) The Wilcoxon Rank Sum Test requires the data to be either ranks or converted to combined ranks, as it is a non-parametric test.
B) Random and independent sampling is necessary for the validity of statistical tests, including the Wilcoxon Rank Sum Test.
C) Both populations should have similar shape and dispersion for the test to be accurate. 
Therefore, all of the above assumptions must be satisfied for the Wilcoxon Rank Sum Test to be appropriate.

To Use the Wilcoxon Rank Sum Test as a Test