Concepts of Simulation Model Testing, Verification and Validation

Abstract

The suitability of a simulation model, in terms of its specific intended application, is an issue of great importance. Errors and uncertainties are always present in any simulation model and model testing and evaluation are inseparable from all the other processes involved in the iterative procedures of model development. Attempting to prove that a given model is “correct” or “valid” is impossible and it must be recognised that all models have limitations. Confidence in a model should increase steadily as it is developed, until the overall performance is judged to be acceptable for the planned application. The user of the simulation model must then have a good understanding of the remaining deficiencies, the performance to be expected from the model and its limitations in terms of the range of conditions over which it can be applied. A distinction is made between the processes of “verification”, which are concerned with the consistency of the simulation with the underlying mathematical model, and “validation” which relates to the degree to which the simulation model is an accurate representation of the corresponding real system. The general principles of model evaluation and testing are discussed within this chapter, including issues that arise in the verification and validation of sub-models.