A Wilcoxon rank sum test for comparing two populations involves two independent samples of sizes 15 and 20.The un-standardized test statistic (that is the rank sum)is T = 225.The value of the standardized test statistic z is:
A)6)0
B)15
C)6)43
D)-1.5

Question

Quizplus · Accepted Answer

The standardized test statistic z is calculated using the formula: z = (T - E(T)) / sqrt(Var(T)), where E(T) is the expected value of the rank sum and Var(T) is the variance. For the Wilcoxon rank sum test, E(T) = n1(n1+n2+1)/2 and Var(T) = n1*n2(n1+n2+1)/12. Substituting the given values, we find z = -1.5.

A Wilcoxon Rank Sum Test for Comparing Two Populations Involves