Controlling excessive waiting times in small service systems with time-varying demand: An extension of the ISA algorithm

In many service systems, the arrival pattern is not constant throughout the day. This raises the question how staffing decisions should be adapted in view of controlling customer's waiting times. Assuming a single-stage queueing system with general abandonment and service times and time-varying demand for service, we suggest a method inspired by the simulation-based Iterative Staffing Algorithm (ISA) proposed by Feldman et al. (2008). The main advantage of our extension is that it enables to control the probability of experiencing an excessive waiting time, in particular in small systems.