ABSTRACT
In Chapter 7, “Verification,” validation was defined as the process of ensuring that a model represents reality at a given confidence level. This means that the simulation practitioner will attempt to create a model that is a reasonable representation of the actual system. However, for a variety of reasons, even painstakingly constructed models may not actually represent reality. This means that no matter how well the practitioner thinks that he or she has debugged and enhanced the model, the model may still not be
suitable for conducting any type of analysis. The inability of the model to represent reality may result from certain actions or omissions on the part of the practitioner with respect to any or all of the following issues:
• Assumptions • Simplifications • Oversights • Limitations
Periodically, the practitioner will have to make modeling assumptions. These assumptions may be made because of lack of knowledge. These types of assumptions may be common when the practitioner is attempting to model a system that does not exist or a process that cannot be observed. Certain assumptions may have to be made with respect to the system components, interactions, and input data. Even if some data are available from designers or vendors, the practitioner will have to assume that the data are valid.
