Simulation and modeling - Old Questions

8.  Describe the process of calibration and validation in detail with example.

Validation is concerned with building the right model. It is utilized to determine that a model is an accurate representation of the real system. It is usually achieved through the calibration of the model.

Calibration means to validate the model with the real system, look out for the places for betterment of the models and revising the model to form next better model repeatedly until a satisfiable model is not achieved. The initial model is developed and is calibrated using Naylor-Finger calibration steps with the real system. It is then revised and a first revision model is generated. The first revision model is then calibrated with the real system. It is revised to form a second revision model. This process is continued until the model becomes acceptable.

Naylor and Finger formulated a three step approach:-

1. Build a model that has high face validity.

2. Validate model assumptions.

3. Compare the model input-output transformations to corresponding input-output transformations for the real system.

The following figure shows the relationship of the model calibration to the overall validation process.

The comparison of the model to reality is carried out by verity of test. Some test are subjective and other are objective.

• Subjective test usually involve people, who are knowledgeable about one or more aspects of the system, making judgments about the model and its output.
• Objective test always require data on the system's behavior plus the corresponding data produced by the model.