The stochastic nature of wireless communication suggests a Markov Decision Process (MDP) as a formalism for identifying and evaluating spectrum control policies. However, in practice numerous factors influence the success or failure of a transmission, so that the applicability of particular MDP models to real spectrum management problems must itself be examined. This paper presents a series of model validation studies in which correspondence between an MDP model and a discrete-event simulation (DES) model is evaluated. We test several hypotheses that together provide a foundation and an exemplar for the idea of using MDPs to guide management of shared spectrum. We conclude that there is sufficient similarity between the performance predictions made by the MDP model and the DES model that MDPs can be used effectively to determine spectrum control policies.