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

Keywords: Performance modeling, Automatic call distributors, Operator services staffing, Heterogeneous
positions, Telephony industry, Multi-purpose operator positions, Automatic call distributor,
ACD, Toll and assist calls, Directory-assistance calls, Classical Erlang-type queueing
models, Expected waiting time, Average operator occupancy, Average occupancies, Simulation
results
(Appears also in Section IX.)
43. Andrews, Bruce H. and Shawn M. Cunningham. L.L. Bean improves call-center forecasting,
Interfaces, 25 (6), 1995, 1–13.
Abstract. Two forecasting models are developed and implemented for use at L.L. Bean Inc.,
a widely known retailer of high-quality outdoor goods and apparel. The models forecast calls
incoming to L.L. Bean’s call center so that efficient staffing schedules for telephone agents can be
produced two weeks in advance. The ARIMA/transfer function methodology is used to model
these time series data since they exhibit seasonal patterns but are strongly influenced by independent
variables, including holiday and advertising interventions. The improved precision of
the models is estimated to save $300,000 annually through enhanced scheduling efficiency.
Keywords: Call center forecasting, L.L. Bean, Forecasting models, Retailer, Telephone agents,
Staffing schedules, ARIMA transfer function methodology, Time series data, Seasonal patterns,
Holiday, Advertising interventions
(Appears also in Section II.)
44. Borst, S.C. Optimal probabilistic allocation of customer types to servers. Proceedings of the
Joint International Conference on Measurement and Modeling of Computer Systems (SIGMET-
RICS95). Ottawa, ON, Canada, 1995, 116–125.
Abstract. The model under consideration consists of n customer types attended by m parallel
non-identical servers. Customers are allocated to the servers in a probabilistic manner; upon
arrival customers are sent to one of the servers according to an m ∗ n matrix of routing probabilities.
We consider the problem of finding an allocation that minimizes a weighted sum of the
mean waiting times. We expose the structure of an optimal allocation and describe for some
special cases in detail how the structure may be exploited in actually determining an optimal
allocation.
Keywords: Probabilistic allocation, Customer types, Servers, Non-identical servers, Routing
probabilities, Parallel servers, Distributed computer systems, Communication networks, Global
scheduling
45. Thompson, G.M. Improved implicit optimal modeling of the labor shift scheduling problem,
Management Science, 41 (4), 1995, 595–607.
Abstract. This paper presents an integer programming model for developing optimal shift
schedules while allowing extensive flexibility in terms of alternate shift starting times, shift
lengths, and break placement. The model combines the work of Moondra (1976) and Bechtold
and Jacobs (1990) by implicitly matching meal breaks to implicitly represented shifts. Moreover,
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