Progressive Refinement

One nice feature of simulation is that models do not have to include all of the final detail before they will run. This allows a progressive refinement strategy to be used in which detail is added to the model in stages rather than all at once. Not only do models get built and running quicker this way, but it also makes models easier to debug. In the initial stages of a model, for example, attractive graphics are not very useful and, since they are likely to be changed anyway, should not be added until later when preparing for the final model presentation.

The complexity of model building should never be underestimated and it is always better to begin simple and add complexity rather than create an entire complex model at once. It is also easier to add detail to a model than it is to remove it from a model. Building a model in stages enables bugs to be more readily identified and corrected. Emphasizing the importance of applying progressive refinement to model building, Law and Kelton (1991) have advised:

Although there are few firm rules on how one should go about the modeling process, one point on which most authors agree is that it is always a good idea to start with a simple model which can later be made more sophisticated if necessary. A model should contain only enough detail to capture the essence of the system for the purposes for which the model is intended: it is not necessary to have a one-to-one correspondence between elements of the model and elements of the system. A model with excessive detail may be too expensive to program and to execute.