Simulation In formulating a stochastic model to describe a real phenomenon it used to be that one compromised between choosing a model that is a realistic replica of the actual situation and choosing one whose mathematical analysis is tractable. That is there did not seem to be any payoff in choosing a model that faithfully conformed to the phenomenon under study if it were not possible to mathematically analyze that model. Similar considerations have led to the concentration on asymptotic or steady state results as opposed to the more useful ones on transient time. However the relatively recent advent of fast and inexpensive computational power has opened up another approach namely to try to model the phenomenon as faithfully as possible and then to rely on a simulation study to analyze it