The Economics Department wishes to develop a multiple regression model to predict student GPA for economics courses. Department faculty have collected data for 112 graduates, which include the variables economics GPA, SAT verbal, SAT mathematics, ACT English, ACT social science, and high school percentile rank. The data are stored in a file named Student GPA on your data disk and described in the Chapter 11 appendix.
a. Use the SAT variables and class rank to determine the best prediction model. Remove any independent variables that are not significant. What are the coefficients, their Student's t statistics, and the model?
b. Use the ACT variables and class rank to determine the best prediction model. Remove any independent variables that are not significant. What are the coefficients, their Student's t statistics, and the model?
c. Which model predicts an economics GPA better? Present the evidence to support your conclusion.