Quality and Reliability Methods - SAS

290 Degradation Chapter 16
Inverse Prediction
• The Generate Report for Current Model button creates a report for the current model settings. See
“Model Reports” on page 296.
The optimization method menu provides three choices for the optimization method (Newton,
QuasiNewton BFGS, and QuasiNewton SR1). For details about the methods, see the Nonlinear Regression
chapter of the Modeling and Multivariate Methods book.
The initial parameter values are shown at the bottom, along with sliders for visualizing how changes in the
parameters affect the model. To do so, first select Graph Options > Show Fitted Lines from the platform
red-triangle menu to show the fitted lines on the plot. Then move the parameter sliders to see how changes
affect the fitted lines. To compute the optimal values for the parameters, click the Fit Model or
Fit by System ID button.
To fix a value for a parameter, check the box under Fixed for the parameter. When fixed, that parameter is
held constant in the model fitting process.
Entering a Model with the Formula Editor
You can use the Formula Editor to enter a model. Click the Edit button to open the Formula Editor to enter
parameters and the model. For details about entering parameters and formulas in the Formula Editor, see
Using JMP.
Figure 16.13 Alternate Model Specification Report
Inverse Prediction
Use the Inverse Prediction tab to predict the time when the Y variable will reach a specified value. These
times are sometime called pseudo failure times. Figure 16.14 shows the Inverse Prediction tab.