The Wilcoxon rank-sum test is an appropriate test when:
A) comparing two population proportions, assuming the underlying distributions are normal.
B) comparing two population medians, assuming both populations are mound-shaped symmetric.
C) comparing two population medians when the underlying distributions are non-normal or when the data are ranks.
D) testing whether the median value from a single population is different from an assumed value when the distribution is normal.

Question

Quizplus · Accepted Answer

The Wilcoxon rank-sum test is also known as the Mann-Whitney U test, and it is used to compare two groups of data to determine if they come from the same population or not. It is a non-parametric test that does not require any assumptions about the underlying distribution of data. Therefore, it is an appropriate test when comparing two population medians when the underlying distributions are non-normal or when the data are ranks. Option A is incorrect because the Wilcoxon rank-sum test does not compare proportions. Option B is incorrect because it assumes that both populations are mound-shaped symmetric, which is a restrictive assumption. Option D is incorrect because it tests whether the median value from a single population is different from an assumed value, not comparing two populations.

The Wilcoxon Rank-Sum Test Is an Appropriate Test When