2 T 114.271 is approximated by the normal distribution. For a large number of ties, Equation 14.26 may not be correct For the data in Table 1418, TX - 93.5 with ET ++1) 10/2011 and 115 Varir) + 1 Notice that the variance of the sampling distribution of the Wikon rank sum statistic, T. in the same as the variance of the sampling distribution of the Mann-Whitney statistic, It follows that T-1115 V 230 - 1:42 - P.Value = 0.1956 Example 14.14 Eamings for Two Firms (Wilcoxon Rank Sum Test) In a study designed to compare the performance of firms that give management forecasts of eamings with the performances of those that do not, independent ran dom samples of O firm from each of the populations were taken. The variability of the growth rate of earnings over the previous 10 periods was measured for each 33 Newpomunte Trata for hidupoedend landown Sangius 611 of the 160 firma, and these variabilities were ranked. The sum of the ranks for firms not disclosing management earnings forecasts was 7,247 (aggi and Grier 1950). Test against a two-sided alternative, the null hypothesis that the central locations of the population distributions of eamings variabilities are the same for these two types of firms. Show that the results are the same with both the Mann-Whitney U test and the Wilcoxon rank um test