Systems development may proceed in two general ways. The more familiar is to fix costs and maximize effectiveness. An alternative is to fix effectiveness and minimize the “costs” in health, safety, manpower, personnel, and training (MPT), and equipment. Isoperformance methodology follows the latter approach and leads naturally to trade-offs among the cost factors. Isoperformance analyses are intended to be implemented as expert systems to aid in decision making through interactive computer programs for use by individual managers. An isoperformance approach does not attempt to replace or eliminate the user as a source of information, but, through expert systems technology, limits input to a small number of estimates. In making these estimates, the user has access to a library of relevant information, and his or her estimates are checked for logical consistency with fact. Output consists of isoperformance curves from which comparisons can be made among the various local components relevant to systems development as they progress through the life cycle. In the present paper, to illustrate the model, we use minimization of simulator sickness incidence as an outcome which can be raised or lowered based on trade-offs made between equipment variables, adaptation and training, and individual predisposing factors. The model can provide a context for future development of an interactive program as a decision aid to managers in the specification of factors in training systems design.