Statistical Monitoring of Service Levels and Staffing Adjustments for Call Centers

Call centers are an indispensable part of many businesses, and their economic role is important and fast growing. To remain competitive, call centers must provide high‐quality services while keeping the number of agents and hence labor costs down. It is thus vital to monitor the service level (SL), which is a common measure of the quality of service, and make suitable staffing adjustments. In this paper, we describe an engineering process control strategy to monitor SL. Staffing is adjusted according to changes in SL. An exponentially weighted moving average for SL based on upper and lower limits is determined from historical data and employed to monitor changes in SL during different time intervals so as to keep the frequency of adjustments to a minimum. Only if SL exceeds its lower or upper limit do we increase or decrease the number of agents for a given interval. Numerical tests show that we can strike a balance between SL and staffing by using our proposed method.