Business Statistics

Chapter 15 | Multiple Regression Analysis 527

15.10 A CASE WHEN THE QUADRATIC REGRESSION MODEL IS A

BETTER ALTERNATIVE TO THE SIMPLE REGRESSION MODEL

Figure 15.31 is the fitted line plot for Example 15.2 (simple regression model) produced using Minitab.

When we compare this with Figure 15.33 which is the fitted line plot for Example 15.2 (Quadratic

regression model) produced using Minitab, we find that the quadratic regression model best defines

the model. The R

2

value for simple linear regression model is 56.6% and the R

2

value for quadratic

regression model is 76.9%. This indicates that the quadratic regression model is a better alternative. ...