# Validating a model

Refer to the Model Simulation VI in the for an example that demonstrates how to simulate the response of an unknown system with the estimated model.Use model prediction to test the ability of the model to predict the response of the system using past input and output data.The SI Model Simulation VI determines the outputs of a system for given inputs.After you build a model for the system using the input and output data you measured, you can use the model to simulate the response of the system by using the model equations. You also can use simulation to validate the model by comparing the simulated response with the measured response.

Some control techniques take advantage of model prediction to improve control performance.Refer to the Model Prediction VI in the -step ahead prediction to verify the model for an unknown system.Use model residual analysis to analyze the prediction error, which is the difference between the response that an estimated model predicts and the actual response from the system.If the value of autocorrelation falls within the confidence range, the autocorrelation value is insignificant and you can consider this value to be equal to zero.The following equation defines the cross correlation between residuals and past inputs.