Comparing performance measures in dynamic job shops: economics vs. time

Recent research has considered the use of economic objectives in production scheduling environments as opposed to the classic time-based measures prevalent in the literature and in practice. This paper presents a comparison of both types of objectives to determine how differently the objectives select scheduling methods and how much economic loss occurs when using time-based measures. A dynamic job shop is modeled using computer simulation to study the problem. Various utilization and due-date allowance settings are considered in the experimental design, along with a variety of time-based and economic objectives and scheduling methods. The results show that percent tardy was the most effective time-based objective in meeting economic goals. However, even with this measure substantial economic loss occurs under certain conditions. In general, the time-based measures do not lead to similar scheduling decisions, while the various economic methods tended to lead to at least "good" economic decisions.