You have been asked to develop a model that will predict the cost with financial aid for students at highly ranked private colleges. The data file Private Colleges contains data collected by a national news service. Variables are identified in the Chapter 12 appendix.
a. Specify a list of potential predictor variables with a short rationale for each variable.
b. Use multiple regression to determine the conditional effect of each of these potential predictor variables.
c. Eliminate those variables that do not have a significant conditional effect to obtain your final model.
d. Prepare a short discussion regarding the conditional effects of the predictor variables in your model, based on your analysis.
Nutrition-Based Mini-Case Studies
The following exercises are based on nutrition research done by the Economic Research Service of the U.S. Department of Agriculture. The data for these exercises are contained in the data file HEI Cost Data Variable Subset, which is described in the Chapter 10 appendix. The data file HEI Cost Data Variable Subset contains considerable information on randomly selected individuals who participated in an extended interview and medical examination. There are two observations for each person in the study. The first observation, identified by daycode = 1, contains data from the first interview, and the second observation, daycode = 2, contains data from the second interview. This data file contains the data for the following exercises. The variables are described in the data dictionary in the Chapter 10 appendix. Each of the multiple regression models in the following exercises should contain a dummy variable that adjusts for possible additive differences between data collected during the two different interviews.