The Utility of Different Types of Models: Crew Size Evaluation in the Maritime Industry

Models can be practical tools for addressing problems with complex systems. Their utility derives from their ability to efficiently relate changes in design parameters to system performance. The term “model” has been used to describe a wide range of qualitative and quantitative approaches to system description, understanding, and prediction. Resolving the confusion generated by the multiple meanings of the term “model” has theoretical and practical importance. This paper defines three classes of models to help resolve this confusion: conceptual, computational, and derivative. Conceptual models identify the underlying constraints and causal structure of a system. Computational models operationalize conceptual models with mathematical formalisms. Derivative models summarize the observations of system behavior to relate design parameters to system performance. These distinctions help define the different resource requirements, benefits, and capabilities associated with each class of model. These different classes are illustrated with an example from the maritime industry.