The main purpose of this paper is to design a control chart for monitoring the service processes in congested immobile single-stage service systems where customer arrivals are time dependent. It is investigated how social and economic/statistical aspects of the control chart can be addressed. As customer satisfaction is a key success factor for a service system, our proposed design method incorporates cost minimization and service quality maximization as two conflicting objective functions to constitute a bi-objective optimization model. The service quality is measured by the waiting time required to obtain a service, and a constraint is considered to guarantee the statistical performance of the control chart. Simulation-based optimization is used to obtain Pareto-optimal designs. A case study of a local restaurant is presented where the daily customers’ data are used to estimate the required parameters. The results show that the proposed method is able to make a trade-off between the quality-control cost and the customer waiting time. They also indicate how the resulting design is sensitive to the misspecification of the input parameters.

本文的主要目的是设计一个控制图，用于监视拥挤的不动单阶段服务系统中客户到达时间与时间有关的服务过程。研究了如何解决控制图的社会和经济/统计问题。由于客户满意度是服务系统成功的关键因素，因此我们提出的设计方法将成本最小化和服务质量最大化作为两个相互冲突的目标函数，从而构成了一个双目标优化模型。服务质量由获得服务所需的等待时间来衡量，并考虑一个约束条件以保证控制图的统计性能。基于仿真的优化用于获得帕累托最优设计。给出了一个当地餐馆的案例研究，其中每天的顾客数据被用来估计所需的参数。结果表明，该方法能够在质量控制成本和客户等待时间之间进行权衡。它们还指出了所得设计如何对输入参数的错误指定敏感。