Qusetion: Expensive ads Consumers who think a product's advertising is expensive often also think the product must be of high quality. Can other information undermine this effect? To find out, marketing researchers did an experiment. The subjects were 90 women from the clerical and administrative staff of a large organization. All subjects read an ad that described a fictional line of food products called "Five Chefs." The ad also described the major TV commercials that would soon be shown, an unusual expense for this type of product. The 45 women who were randomly assigned to the control group read nothing else. The 45 in the "undermine group" also read a news story headlined "No Link between Advertising Spending and New Product Quality." All the subjects then rated the quality of Five Chefs products on a 7-point scale. The study report said, "The mean quality ratings were significantly lower in the undermine treatment (x¯A = 4.56) than in the control treatment (x¯C = 5.05; t = 2.64, P
(a) The 90 women who participated in the study were not randomly selected from a population. Explain why the Random condition is still satisfied.
(b) The distribution of individual responses is not Normal, because there is only a 7-point scale. What is the shape of the sampling distribution of x¯C - x¯A? Explain.
(c) Interpret the P-value in context.