Operations Research
The Fourier-series method for inverting transforms of probability distributions
Queueing Systems: Theory and Applications - Numerical computations in queues
Management Science
Commissioned Paper: Telephone Call Centers: Tutorial, Review, and Research Prospects
Manufacturing & Service Operations Management
Modeling Daily Arrivals to a Telephone Call Center
Management Science
Fluid Models for Multiserver Queues with Abandonments
Operations Research
The Impact of Delay Announcements in Many-Server Queues with Abandonment
Operations Research
The Impact of Delay Announcements in Many-Server Queues with Abandonment
Operations Research
Call Centers with Delay Information: Models and Insights
Manufacturing & Service Operations Management
The Impact of Delaying the Delay Announcements
Operations Research
Delay predictors for customer service systems with time-varying parameters
Proceedings of the Winter Simulation Conference
Manufacturing & Service Operations Management
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Motivated by interest in making delay announcements to arriving customers who must wait in call centers and related service systems, we study the performance of alternative real-time delay estimators based on recent customer delay experience. The main estimators considered are: (i) the delay of the last customer to enter service (LES), (ii) the delay experienced so far by the customer at the head of the line (HOL), and (iii) the delay experienced by the customer to have arrived most recently among those who have already completed service (RCS). We compare these delay-history estimators to the standard estimator based on the queue length (QL), commonly used in practice, which requires knowledge of the mean interval between successive service completions in addition to the QL. We characterize performance by the mean squared error (MSE). We do an analysis and conduct simulations for the standard GI/M/s multiserver queueing model, emphasizing the case of large s. We obtain analytical results for the conditional distribution of the delay given the observed HOL delay. An approximation to its mean value serves as a refined estimator. For all three candidate delay estimators, the MSE relative to the square of the mean is asymptotically negligible in the many-server and classical heavy-traffic (HT) limiting regimes.