Practice of Management Science---GYMJAC: One Company's Solution to a Classical Problem in Group Planning and Decision-Making

GYMJAC is a family of computer simulation models, devised by Schreiber technical staff, with the active participation of the managers, who now use the models to aid in planning and decision-making. The models are used to evolve basic profiles of the production facilities required to meet variable sales volumes under a wide variety of possible operational conditions. The name “GYMJAC” is Schreiber's. It points to the genesis of, and original motivation behind the models. Quite simply, the models were intended to serve as a gymnasium (GYM) in which the Schreiber plant manager referred to in this article, Jack (JAC), could exercise, test, and improve his thinking about facilities requirements. The system employed for model building was the Interactive Financial Planning System, IFPS.The models are stored by, and accessed through a contract time-sharing service. They are used on-line in an interactive or conversational mode, and the format of each model is designed so that a manager can work with it directly with little or no assistance. He converses with one or more of the models until he is confident that the information obtained suits his needs.Although this article describes the overall structure and workings of the system as a whole, its main purpose is to report the GYMJAC experience at Schreiber. The authors feel that the ingredients which made this experience possible---problem situation, management attitudes, design philosophy---are of general interest, and that they may well help others with a similar problem situation to see new light at the end of the tunnel.