Methods for the external validation of contiuous system simulation models:a review

External validation is an integral part of the process of simulation model development. Many methods of external validation of continuous system simulation models have been proposed and, inevitably, the approach selected in any given application is highly dependent upon the purpose of the model and the associated accuracy requirements. Although the process of external validation has subjective aspects, formalisation of methods in some safety-critical fields of application has provided a basis for the development of objective measures of model performance. Such measures can be applied in other application areas and allow the whole process of assessing model credibility to be put on a firmer foundation. This paper reviews available methods, discusses practical issues that can arise in the application of these validation techniques and gives a brief account of some validation problems in selected application areas.