A stock analyst wants to determine whether there is a difference in the mean rate of return for three types of stock: utility, retail, and banking stocks. The following output is obtained:
Analysis of Variance
Source DF SS MS F P
Factor 2 86.49 43.25 13.09 0.001
Error 13 42.95 3.30
Total 15 129.44
Level N Mean St. Dev ---------+------------+-------------+--------
Utility 5 17.400 1.916 (------*--------)
Retail 5 11.620 0.356 (------*--------)
Banking 6 15.400 2.356 (------*-------)
Pooled st dev = 1.818 ---------+------------+-------------+--------
Find the 95% confidence interval for the difference between the mean rates of return for the utility and the retail stocks.