Which of the following statements about the two-sample Wilcoxon rank sum test is/are FALSE? A)The samples must each be independent simple random samples. B)The observations from the combined samples are placed in rank order. C)The Wilcoxon rank sum statistic is the sum,W,of the ranks for the observations in the first sample. D)The distribution of W has mean If the populations are Normally distributed. E)The hypothesis that the two populations have identical distributions is rejected when the statistic W is far from its mean.

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Statement D is false. The distribution of W has mean equal to n1(n1+n2+1)/2, where n1 and n2 are the sample sizes of the first and second samples, respectively. The distribution of W is approximately Normal when the sample sizes are large and the populations have similar shapes.

Which of the Following Statements About the Two-Sample Wilcoxon Rank