An advertising agency has been hired by a manufacturer of pens to develop an advertising campaign for the upcoming holiday season. To prepare for this project, the research director decides to initiate a study of the effect of advertising on product perception. An experiment is designed to compare five different advertisements. Advertisement A greatly undersells the pen's characteristics. Advertisement B slightly undersells the pen's characteristics. Advertisement C slightly oversells the pen's characteristics. Advertisement D greatly oversells the pen's characteristics. Advertisement E attempts to correctly state the pen's characteristics.
A sample of 30 adult respondents, taken from a larger focus group, is randomly assigned to the five advertisements (so that there are six respondents to each). After reading the advertisement and developing a sense of product expectation, all respondents unknowingly receive the same pen to evaluate. The respondents are permitted to test the pen and the plausibility of the advertising copy. The respondents are then asked to rate the pen from l to 7 on the product characteristic scales of appearance, durability, and writing perfor¬mance. The combined scores of three ratings (appearance, durability, and writing performance) for the 30 respondents are stored in Pen. These data arc:

a. At the 0.05 level of significance, is there evidence of a difference in the median ratings of the five advertisements?
b. Compare the results of (a) with those of Problem 11.10 (a) on page 402.
c. Which test is more appropriate for these data: the Kruskal-Wallis rank test or the one-way ANOVA F test? Explain.