User:Johnsteen/sandbox

Verification, Validation, and Calibration of a computer simulation model are conducted during the building of a simulation model to improve its accuracy and credibility. "Simulation models are increasingly being used to solve problems and to aid in decision-making. The developers and users of these models, the decision makers using information obtained from the results of these models, and the individuals affected by decisions based on such models are all rightly concerned with whether a model and its results are “correct”". This concern is addressed through verification, validation, and calibration of the simulation model.

The simulation models are approximate imitations of real-world systems and they never exactly imitate the real-world system. Due to that a model should be verified and validated to the degree needed for the models intended purpose or application.

The verification, validation, and calibration of simulation model starts after functional specifications have been documented and initial model development has been completed. Verification, validation, and calibration is an iterative process that takes place throughout the building of a model.

Verification
In the context of computer simulation verification of a computer model is the process of confirming it is correctly implemented with respect to the conceptual model (it matches specifications and assumptions deemed acceptable). During verification the model is tested to find and fix errors in the implementation of the model. Various processes and techniques are used to assure the model matches specifications and assumptions with respect to the model concept. The objective of model verification is to ensures that the implementation of the model is correct.

Validation
Validation checks the accuracy of the model's representation of the real system. Model validation is defined to mean “substantiation that a computerized model within its domain of applicability possesses a satisfactory range of accuracy consistent with the intended application of the model”. There are several approaches to determining the validity of a model.

Validation Techniques
There are many techniques used to validate a computer model. The techniques range from subjective reviews to objective statistical tests.

A common approach is to have the model builders determine validity of the the model through a series of tests.

A simulation model that has face validity appears to be a reasonable imitation of the real-world system to people who are knowledgeable of the real world system. Face validity is tested by having the users examine model output for reasonableness and in the process identifying deficiencies. An added advantage of have the users involved in validation is that the model's credibility or user's confidence in the model will increase.

Calibration
Calibration adjusts the model to increase its accuracy. After calibration the verification and validation of the model may need to be reassessed.