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

108. Masi, Denise M. Bevilacqua, Martin Fisher and Carl M. Harris. Computation of steady-state
probabilities for resource sharing call center queueing systems, Stochastic Models [online], 17 (2),
2001 [viewed July 24, 2001].
Abstract. Two routing rules for a queueing system of two stations are considered as alternative
models for modeling a call-center network. These routing rules allow customers to switch queues
under certain server and other resource availability conditions, either external to the system upon
arrival to the network, or internal to the system after arrival to a primary call center. Under
the assumption of Poisson arrivals and exponentially distributed service times, these systems are
analyzed using matrix-geometric techniques, yielding a non-trivial set of ergodicity conditions
and the steady-state joint probability distribution for the number of customers at each station.
An extensive numerical analysis is conducted, yielding some physical insight into these systems
and related generalizations.
109. Shumsky, R. and E. Pinker. Gatekeepers and referrals in services. Working paper OP01-02,
Simon School, University of Rochester, 2001.
Abstract. We examine services in which customers encounter a gatekeeper who makes an initial
diagnosis of the customer’s problem and then may refer the customer to a specialist. The gatekeeper
may also attempt to solve the problem, but the probability of treatment success decreases
as the problem’s complexity increases. Given the costs of treatment by the gatekeeper and the
specialist, we find the firm’s optimal referral rate from a particular gatekeeper to the specialists.
We then consider the principal-agent problem that arises when the gatekeeper, but not the firm,
observes the gatekeeper’s treatment ability as well as the complexity of each customer’s problem.
We examine the relative benefits of compensation systems designed to overcome the effects
of this information asymmetry and identify when bonuses based solely on referral rates do not
ensure first-best system performance. We also consider the value of such output-based contracts
when gatekeepers are heterogeneous in ability, so that two gatekeepers face different probabilities
of treatment success when given the same problem. Finally, we compare environments in which
the gatekeeper is, and is not, faced with risk in the form of significant variance in compensation.
110. Atlason, Julius, Marina A. Epelman and Shane G. Henderson. Combining simulation and cutting
plane methods in service systems. Proceedings of the 2002 National Science Foundation
Design, Service and Manufacturing Grantees Conference, 2002.
Abstract. In this paper we describe a method that combines simulation and cutting plane
methods to solve resource allocation and scheduling problems. We solve a relaxed linear (integer)
program iteratively and pass the solution of each iteration to a simulation. The results
of the simulation are used to generate constraints in the linear (integer) program. We provide
conditions under which the solutions of the linear (integer) program converges to an optimal
solution of the unrelaxed problem. The concavity of the underlying service level function is
critical for the method and we present a linear programming method to numerically check the
concavity of a function.
111. Chen, Bert P.K. and Shane G. Henderson. Two issues in setting call centre staffing levels, Annals
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