Movie studios often release films into selected markets and use the reactions of audiences to plan further promotions. In these data, viewers rate the film on a scale that assigns a score from 0 (dislike) to 100 (great) to the movie. The viewers are located in one of three test markets: urban, rural, and suburban. The groups vary in size.
(a) Plot the data. Do the data appear suited to ANOVA?
(b) From your visual inspection, do differences among the average ratings appear large when compared to the within-group variation?
(c) Fit a multiple regression of rating on two dummy variables that identify the urban and suburban viewers. Interpret the estimated intercept and slopes.
(d) Are the standard errors of the slopes equal, as in the text example of wheat yields? Explain why or why not.
(e) Does a statistical test agree with your visual impression of the differences among the groups? Test the null hypothesis that the ratings are the same in the three markets.
(f) Do these data meet the conditions required for an ANOVA?
(g) What conclusions should the studio reach regarding the prospects for marketing this movie in the three types of markets?