Independent random samples of sizes nA = 4 and nB = 2 are taken from two continuous populations.
(a) Enumerate all possible collections of ranks associated with the smaller sample in the combined sample ranking. Attach probabilities to these rank collections under the null hypothesis that the populations are identical.
(b) Obtain the null distribution of Ws = sum of ranks of the smaller sample. Verify that the tail probabilities agree with the tabulated values.