Dynamic simulation models: how valid are they?

In a strict sense, the subject of dynamic simulation model validity can be treated thoroughly and quickly: there are no fully valid models because all models are something less than the object, or system, being modeled. For example, millions of people have a conceptual model of the President, but, like fingerprints, no two of these models is exactly the same. Further, none matches precisely every detail of the real system. The same reasoning applies to all types and kinds of models of drug abuse.