Question: Stocks are classified as conservative (C), moderately aggressive (M), or aggressive (A). Suppose a random sample of stocks from each of these categories was selected and the returns tracked over a six-month period. The data can be found in the file stocks.mtp (or stocks.xls) on doc-depot.

(a) Test whether the data show evidence of real differences in average returns among the different categories of stocks. Use the .05 level of significance.

(b) Examine the residuals to see if the assumptions underlying the analysis of variance model are justified.

(c) Using the Bonferroni adjustment, calculate confidence intervals for all the pairwise differences between the three types of stocks. Now use Minitab to calculate the Tukey pairwise confidence intervals. What do you conclude?

(d) Use the Kruskal-Wallis test in Minitab to test for differences in the median returns among the three types of stocks