Introduction to queueing theory (2nd ed)
Introduction to queueing theory (2nd ed)
On the M(n)/M(n)/s queue with impatient calls
Performance Evaluation
A model for rational abandonments from invisible queues
Queueing Systems: Theory and Applications
Asymptotic Results and a Markovian Approximation for the M(n)/M(n)/s+GI System
Queueing Systems: Theory and Applications
A Diffusion Approximation for a Markovian Queue with Reneging
Queueing Systems: Theory and Applications
Designing a Call Center with Impatient Customers
Manufacturing & Service Operations Management
Commissioned Paper: Telephone Call Centers: Tutorial, Review, and Research Prospects
Manufacturing & Service Operations Management
Dimensioning Large Call Centers
Operations Research
Heavy Traffic Limits for Queues with Many Deterministic Servers
Queueing Systems: Theory and Applications
Rational Abandonment from Tele-Queues: Nonlinear Waiting Costs with Heterogeneous Preferences
Queueing Systems: Theory and Applications
Engineering Solution of a Basic Call-Center Model
Management Science
A Method for Staffing Large Call Centers Based on Stochastic Fluid Models
Manufacturing & Service Operations Management
Fluid Models for Multiserver Queues with Abandonments
Operations Research
Two fluid approximations for multi-server queues with abandonments
Operations Research Letters
Call-Routing Schemes for Call-Center Outsourcing
Manufacturing & Service Operations Management
Monotonicity Properties For Multiserver Queues With Reneging And Finite Waiting Lines
Probability in the Engineering and Informational Sciences
QBD approximations of a call center queueing model with general patience distribution
Computers and Operations Research
A time-varying call center design via lagrangian mechanics
Probability in the Engineering and Informational Sciences
Manufacturing & Service Operations Management
The Impact of Delay Announcements in Many-Server Queues with Abandonment
Operations Research
Service Interruptions in Large-Scale Service Systems
Management Science
Customer Abandonment in Many-Server Queues
Mathematics of Operations Research
Tail asymptotics for waiting time distribution of an M/M/s queue with general impatient time
Proceedings of the 5th International Conference on Queueing Theory and Network Applications
Designing a call center with an IVR (Interactive Voice Response)
Queueing Systems: Theory and Applications
Call Centers with Delay Information: Models and Insights
Manufacturing & Service Operations Management
Refining Square-Root Safety Staffing by Expanding Erlang C
Operations Research
Queues with Many Servers and Impatient Customers
Mathematics of Operations Research
Large-Scale Service Marketplaces: The Role of the Moderating Firm
Management Science
Heavy-traffic analysis of cloud provisioning
Proceedings of the 24th International Teletraffic Congress
Fluid models of many-server queues with abandonment
Queueing Systems: Theory and Applications
An Overloaded Multiclass FIFO Queue with Abandonments
Operations Research
Loss ratio of the EDF scheduling policy with early discarding technique
Information Processing Letters
Critically Loaded Time-Varying Multiserver Queues: Computational Challenges and Approximations
INFORMS Journal on Computing
Mathematics of Operations Research
Dynamic scheduling of a GI/GI/1+GI queue with multiple customer classes
Queueing Systems: Theory and Applications
Data-stories about (im)patient customers in tele-queues
Queueing Systems: Theory and Applications
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The subject of the present research is the M/M/n + G queue. This queue is characterized by Poisson arrivals at rate 驴, exponential service times at rate 驴, n service agents and generally distributed patience times of customers. The model is applied in the call center environment, as it captures the tradeoff between operational efficiency (staffing cost) and service quality (accessibility of agents).In our research, three asymptotic operational regimes for medium to large call centers are studied. These regimes correspond to the following three staffing rules, as 驴 and n increase indefinitely and 驴 held fixed: Efficiency-Driven (ED): $$n\ \approx \ (\lambda / \mu)\cdot (1 - \gamma),\gamma 0,$$ Quality-Driven (QD): $$n \ \approx \ ( \lambda / \mu)\cdot (1 + \gamma),\gamma 0$$ , and Quality and Efficiency Driven (QED): $$ n \ \approx \ \lambda/ \mu+\beta \sqrt{\lambda/\mu},-\infty .In the ED regime, the probability to abandon and average wait converge to constants. In the QD regime, we observe a very high service level at the cost of possible overstaffing. Finally, the QED regime carefully balances quality and efficiency: agents are highly utilized, but the probability to abandon and the average wait are small (converge to zero at rate 1/ $$\sqrt{n}$$ ).Numerical experiments demonstrate that, for a wide set of system parameters, the QED formulae provide excellent approximation for exact M/M/n + G performance measures. The much simpler ED approximations are still very useful for overloaded queueing systems.Finally, empirical findings have demonstrated a robust linear relation between the fraction abandoning and average wait. We validate this relation, asymptotically, in the QED and QD regimes.