CALL CENTERS (CENTRES) - Faculty of Industrial Engineering and ...

customer from the unprotected queue will be started if the protected queue is empty and more
than a given number of servers become idle. The model is a generalization of the many-server
queue with impatient customers. The global balance conditions seem to have no explicit solution.
However, the balance conditions for the density of the stationary state process for the subsystem
of customers being in service or in the protected queue can be solved. This yields the stability
conditions and the probabilities that precisely n customers are in service or in the protected
queue. For obtaining performance measures for the unprotected queue, a system approximation
based on fitting impatience intensities is constructed. The results are applied to the performance
analysis of a call center with an integrated voice-mail server.
Keywords: Two-queue priority system, Call center, s-server priority system, Arrival rates, Service
rate, Random maximal waiting time, Many-server queue, Global balance conditions, Stability
conditions, Performance analysis, Integrated voice-mail server
69. Coffman, S. and M.L. Saxton. Staffing the reference desk in the largely-digital library, Reference
Librarian, 66, 1999, 141–161.
Abstract. The article examines how a centralized, networked reference service might improve
efficiency and reduce costs by addressing two long-standing and seemingly intractable problems
associated with the reference process: that librarians spend only a small portion of their time at
the reference desk actually answering questions, and that many of the questions they do answer
could be handled by paraprofessionals. The authors explore the feasibility of a live, centralized,
networked reference service in a library setting by comparing traditional reference services at the
County of Los Angeles Public Library with a commercial inbound call center designed to handle
the same volume of questions. Applying Erlang C, the standard algorithm used to calculate
staffing requirements for commercial call centers, the authors find that a networked reference
service based on a call center model could reduce the reference staff requirements at the County
of Los Angeles Public Library by 42% or more. These results are very preliminary, and the
article cautions against jumping to conclusions until we have much better data on the questions
we are answering and the reference process as a whole, but the evidence we do have suggests
that networked reference services have the potential to truly revolutionize the way we have been
doing reference for the past 100 years.
Keywords: Reference desk staff, Largely digital library, Networked reference service, Intractable
problems, Reference process, Librarians, Paraprofessionals, Library setting, Traditional reference
services, County of Los Angeles Public Library, Commercial inbound call center, Erlang-C,
Standard algorithm, Staffing requirements, Call center model, Reference staff requirements
(Appears also in Sections IV and VII.)
70. Gans, Noah and Yong-Pin Zhou. Managing learning and turnover in employee staffing. Working
Paper, The Wharton School, The University of Pennsylvania, July 1999 (Revised November
2000).
Abstract. We study the employee staffing problem in a service organization that uses employee
service capacities to meet random, nonstationary service requirements. The employees experience
learning and turnover on the job, and we develop a Markov Decision Process (MDP) model
that explicitly represents the stochastic nature of these effects. Theoretical results are developed
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