Recall that in Exercise 10.32 (page 417) we compared preexposure and postexposure attitude scores for an advertising study by using a paired difference / test. The data obtained and related Excel add-in (MegaStat) output are shown in Table 18.6 on the next page. Use the Wilcoxon signed ranks test and the MegaStat output to determine whether the distributions of preexposure and postexposure attitude scores are different. Use α = .05.
TABLE 18.6
Preexposure and Postexposure Attitude Scores for an Advertising Study

Preexposure Postexposure Attitude Subject Attitudes (A) Attitudes (A2) Change (d) 50 25 30 50 60 80 45 30 65 70 27 38 61 85 45 31 72 78 9 10