Question: The Western State Tourist Association gives out pamphlets, maps, and other tourist-related information to people who call a toll-free number and request the information. The association orders the packets of information from a document-printing company and likes to have enough available to meet the immediate need without having too many sitting around taking up space. The marketing manager decided to develop a multiple regression model to be used in predicting the number of calls that will be received in the coming week. A random sample of 12 weeks is selected, with the following variables:
y = Number of calls
x1 = Number of advertisements placed the previous week
x2 = Number of calls received the previous week
x3 = Number of airline tour bookings into Western cities for the current week
These data are in the data file called Western States.
a. Develop the multiple regression model for predicting the number of calls received, using backward elimination stepwise regression.
b. At the final step of the analysis, how many variables are in the model?
c. Discuss why the variables were removed from the model in the order shown by the stepwise regression.