86 Study of recall of TV commercials. The Journal of Applied Psychology (June 2002) conducted a study of recall of television commercials. Participants were assigned to watch one of three types of TV programs, with nine commercials embedded in each show. Group V watched a TV program with a violent-content code rating Group S viewed a show with a sex-content code rating, and Group N watched a neutral TV program with neither a V nor an S rating. The dependent variable measured for each participant was the score ( y ) on his or her recall of the brand names mentioned in the commercial messages, with scores ranging from 0 (no brands recalled) to 9 (all brands recalled).
The data are saved in the TVADRECALL file.

a. Write a model for E ( y ) as a function of viewer group.

b. Fit the model you wrote in part a to the data saved in the TVADRECALL file. Give the least squares prediction equation.

c. Conduct a test of overall model utility at a = .01.
Interpret the results. Show that the results agree with the analysis performed in Exercise 10.33.

d. The sample mean recall scores for the three groups were yV = 2.08, yS = 1.71, and yN = 3.17. Show how to find these sample means by using only the b -estimates obtained in part b .