Example Using Stepwise Regression

The Fitness.jmp data table contains the results of an aerobic fitness study. Aerobic fitness can be evaluated using a special test that measures the oxygen uptake of a person running on a treadmill for a prescribed distance. However, it would be more economical to find a formula that uses simpler measurements that evaluate fitness and predict oxygen uptake. To identify such an equation, measurements of age, weight, run time, and pulse were taken for 31 participants who ran 1.5 miles.

Note: For purposes of illustration, certain values of MaxPulse and RunPulse have been changed from data reported by Rawlings (1988, p.105).

Select Help > Sample Data Library and open Fitness.jmp.

Select Analyze > Fit Model.

Select Oxy and click Y.

Select Weight, Runtime, RunPulse, RstPulse, MaxPulse, and click Add.

For Personality, select Stepwise.

Figure 5.1 Completed Fit Model Launch Window

Validation is available only in JMP Pro.

Click Run.

Figure 5.2 Stepwise Report Window

To find a good oxygen uptake prediction equation, you need to compare many different regression models. Use the options in the Stepwise report window to search through models with combinations of effects and choose the model that you want.