14. Advertising: Newspapers Does the newspaper section in which an ad is placed make a difference in the average daily number of people responding to the ad? Is there a difference in average daily number of people responding to the ad if it is placed in the Sunday newspaper as compared with the Wednesday newspaper?

Video Entertainment is a video club that sells videotapes featuring movies of all kinds—instructional videos, videos of TV specials, etc. To attract new customers, Video Entertainment ran ads in the Wednesday newspaper and in the Sunday newspaper offering six free videotapes or DVDs to new members. In addition, the ads were placed in the sports section, the entertainment section, and the business section of the local newspaper. Ads running in the different sections carried different promotion codes. Different codes also were used for Wednesday ads compared with Sunday ads. The numbers of people responding to the ads for days selected at random were recorded according to the promotion codes. The results follow:

Section of Newspaper Day Sports Entertainment Business Wed. 12 12 15 15 11 20 22 22 14 18 17 12 2

5 4

0 3

1 Sun. 20 33 23 15 25 17 32 31 26 25 28 41 13 15 16 14 13 10

(a) List the factors and the number of levels for each factor.

(b) Use the following Minitab printout and the F distribution table (Table 8 of Appendix II) to test for interaction between the variables. Use a 1%

level of significance.

Minitab Printout for Mean Number of Responses per Day Analysis of Variance for Response Source DF SS MS F P Day 1 1024.0 1024.0 55.28 0.000 Section 2 1573.6 786.8 42.48 0.000 Interaction 2 38.0 19.0 1.03 0.371 Error 30 555.7 18.5 Total 35 3191.2

(c) If there is no evidence of interaction between the factors, test for a difference in mean number of daily responses for the levels of the day factor.

Use a 5 0.01.

(d) If there is no evidence of interaction between the factors, test for a difference in mean number of daily responses for the levels of the section factor.

Use a 5 0.01.