User`s guide

8 Model Analysis
Over view of Model Validation and Plots
In this section...
“When to Validate Models” on page 8-2
“Ways to Validate Models” on page 8-2
“Data for Validating Models” on page 8-4
“Supported Model Plots” on page 8-4
“Plotting Models in the GUI” on page 8-5
“Getting Advice About Models” on page 8-7
When to Validate Models
After es timating each m odel, you can validate whether the model reproduces
system behavior within acceptable bounds. You iterate between estimation
and validation until you find the simplest model that best captures the system
dynamics.
For ideas on how to adjust your modeling strategy based on validation results,
see “Troubleshooting Models” on page 8-67.
Tip If you have installed the Control System T oolbo x product, you can also
view models using the LTI Viewer. For more information, see “Viewing Model
Response Using the LTI V iewer” on page 10-5.
Ways to Validate Models
You can use the f ollowing app r oaches to validate models:
• Comparing simulated or predicted model output to measured output.
See “U sing Mo del Output Plots to Validate and Co mpare Models” on page
8-8.
• Analyzing autocorrelation and cross-correlation of the residuals with input.
See “Using Residual Analysis Plots to Validate M odels” on page 8-16.
8-2