In search of a valid view of model validation for operations research

The authors present a general perspective for the purpose of positioning each paper that appears in this Special Issue on ‘Model Validation in Operational Research’. They also raise the question of why the problem of model validation resurfaces from time to time. The pertinent literature suggests that model validation has traditionally been treated from the perspective of efficiency (doing things right). The perspective of effectiveness (doing the right things), on the other hand, has been neglected or completely ignored. This Special Issue is more on the side of effectiveness. The effectiveness perspective addresses itself to the basic question of knowing what a valid model is about and thus necessarily referring to the field of epistemology. Within this general framework, each paper appearing in this special issue is very briefly presented and commented on.