Quality and Reliability Methods - SAS

Chapter 16 Degradation 285
Model Specification
To facilitate explaining the Nonlinear Path Model Specification, open the Device B.jmp data table. The data
consists of power decrease measurements taken on 34 units, across four levels of temperature. Follow these
steps:
1. Open the Device B.jmp data table in the Reliability folder of Sample Data.
2. Select Analyze > Reliability and Survival > Degradation.
3. Select Power Drop and click Y, Response.
4. Select Hours and click Time.
5. Select Degrees C and click X.
6. Select Device and click Label, System ID.
7. Click OK.
Figure 16.6 shows the initial overlay plot of the data.
Figure 16.6 Device B Overlay Plot
The degradation paths appear linear for the first several hundred hours, but then start to curve. To fit a
nonlinear model, select Degradation Path Style > Nonlinear Path from the platform red triangle menu to
show the Nonlinear Path Model Specification outline. See Figure 16.7.
Note: The Edit button shown in the Model Specification window provides access to the Formula Editor, an
interactive alternative for creating formulas. To show the button, select File > Preferences > Platforms >
Degradation > Use Interactive Formula Editor.