The Many Faces of Simulation [Guest editor´s introduction]

The meaning of computer simulation, like beauty, rests in the eyes of the beholder. To the practitioner of econometrics, a model may be a complex algorithm, and he will simulate the prosperity (or poverty) of municipalities, states, and nations on the basis of the different values of the variables. Others have defined simulation as "the development and use of models to aid in the evaluation of ideas and the study of dynamic systems or situations."¹The first paper in this issue will provide another definition. Obviously, more definitions could be quoted, but of one thing we can be certain: simulation provides a laboratory in which we can test proposals without subjecting ourselves to the penalties of trial in the real world. These penalties, in cost and time, have provided the motivation for developing the art of simulation.