Evaluating the impact of operating conditions on the performance of appointment scheduling rules in service systems

The general practice in implementing an appointment scheduling rule (ASR) is to enforce a certain rule, such as "block appointment", to schedule customer arrivals in service systems. The operating environments of service systems are expected to affect considerably the performance of a selected ASR. The objective of this paper is to evaluate the impact of the environmental factors which include probability of no-show (rho), the coefficient of variation (C-v) of service times, and the number of customers per service session (N). The extent to which a certain environmental factor affects the performance of ASR is examined to see if there is any ASR that performs well under most operating conditions. Under situations characterized by 27 different combinations of the factors rho, C-v, and N, the performance of nine scheduling rules are evaluated by a simulation study. The simulation results show that an ASR designed to reduce customer waiting time performs very well in most operating environments considered. One commonly used ASR in real-world service systems, which schedules several customers to arrive at the start of each service session, tends to induce long customer waiting time. (C) 1999 Elsevier Science B.V. All rights reserved.