13. Reconsider the situation described in Exercise 100 of Chapter 10 and the accompanying MINITAB output (the Greek letter eta is used to denote a median).

Mann–Whitney Confidence Interval and Test good N  8 Median  0.540 poor N  8 Median  2.400 Point estimate for ETA1-ETA2 is 1.155 95.9 Percent CI for ETA1-ETA2 is(3.160,

0.409) W  41.0 Test of ETA1  ETA2 vs ETA1  ETA2 is significant at 0.0027

a. Verify that the value of MINITAB s test statistic is correct.

b. Carry out an appropriate test of hypotheses using a signi cance level of .01.