Operations, Information and Decisions Papers

Document Type

Journal Article

Date of this Version


Publication Source

Journal of the American Statistical Association





Start Page


Last Page





A call center is a service network in which agents provide telephone-based services. Customers who seek these services are delayed in tele-queues. This article summarizes an analysis of a unique record of call center operations. The data comprise a complete operational history of a small banking call center, call by call, over a full year. Taking the perspective of queueing theory, we decompose the service process into three fundamental components: arrivals, customer patience, and service durations. Each component involves different basic mathematical structures and requires a different style of statistical analysis. Some of the key empirical results are sketched, along with descriptions of the varied techniques required. Several statistical techniques are developed for analysis of the basic components. One of these techniques is a test that a point process is a Poisson process. Another involves estimation of the mean function in a nonparametric regression with lognormal errors. A new graphical technique is introduced for nonparametric hazard rate estimation with censored data. Models are developed and implemented for forecasting of Poisson arrival rates. Finally, the article surveys how the characteristics deduced from the statistical analyses form the building blocks for theoretically interesting and practically useful mathematical models for call center operations.

Copyright/Permission Statement

This is an Accepted Manuscript of an article published by Taylor & Francis in Journal of the American Statistical Association on 31 Dec 2011, available online: http://wwww.tandfonline.com/10.1198/016214504000001808


abandonment, arrivals, call center, censored data, Erlang-A, Erlang-C, human patience, Inhomogeneous poisson process, Khintchine–Pollaczek formula, lognormal distribution, multiserver queue, prediction of poisson rates, queueing science, queueing theory, service time


Date Posted: 27 November 2017