Heavy Traffic Limits for Queues with Many Deterministic Servers
Queueing Systems: Theory and Applications
Variational optimization for call center staffing
Proceedings of the 2005 conference on Diversity in computing
Dynamic Routing in Large-Scale Service Systems with Heterogeneous Servers
Queueing Systems: Theory and Applications
Call Centers with Impatient Customers: Many-Server Asymptotics of the M/M/n + G Queue
Queueing Systems: Theory and Applications
Modeling and simulation of call centers
WSC '05 Proceedings of the 37th conference on Winter simulation
Evaluating arrival rate uncertainty in call centers
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Contact Centers with a Call-Back Option and Real-Time Delay Information
Operations Research
Managing Response Time in a Call-Routing Problem with Service Failure
Operations Research
Using simulation to predict market behavior for outbound call centers
Proceedings of the 39th conference on Winter simulation: 40 years! The best is yet to come
Corrected asymptotics for a multi-server queue in the Halfin-Whitt regime
Queueing Systems: Theory and Applications
On the staffing policy and technology investment in a specialty hospital offering telemedicine
Decision Support Systems
A time-varying call center design via lagrangian mechanics
Probability in the Engineering and Informational Sciences
Manufacturing & Service Operations Management
Cross-Selling in a Call Center with a Heterogeneous Customer Population
Operations Research
On a Data-Driven Method for Staffing Large Call Centers
Operations Research
Service Interruptions in Large-Scale Service Systems
Management Science
Pricing and Dimensioning Competing Large-Scale Service Providers
Manufacturing & Service Operations Management
When Promotions Meet Operations: Cross-Selling and Its Effect on Call Center Performance
Manufacturing & Service Operations Management
Exploiting Market Size in Service Systems
Manufacturing & Service Operations Management
Optimality analysis of energy-performance trade-off for server farm management
Performance Evaluation
Designing a call center with an IVR (Interactive Voice Response)
Queueing Systems: Theory and Applications
Toward simulation-based real-time decision-support systems for emergency departments
Winter Simulation Conference
Simulation-based models of emergency departments:: Operational, tactical, and strategic staffing
ACM Transactions on Modeling and Computer Simulation (TOMACS)
Exploiting network effects in the provisioning of large scale systems
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A lower bound for the Erlang C formula in the Halfin---Whitt regime
Queueing Systems: Theory and Applications
Refining Square-Root Safety Staffing by Expanding Erlang C
Operations Research
Routing to Manage Resolution and Waiting Time in Call Centers with Heterogeneous Servers
Manufacturing & Service Operations Management
Outsourcing a Two-Level Service Process
Management Science
Heavy-traffic analysis of cloud provisioning
Proceedings of the 24th International Teletraffic Congress
Queueing Systems: Theory and Applications
Does the Erlang C model fit in real call centers?
Proceedings of the Winter Simulation Conference
Dynamic Rightsizing with Quality-Controlled Algorithms in Virtualization Environments
International Journal of Grid and High Performance Computing
Computers and Industrial Engineering
Scaled control in the QED regime
Performance Evaluation
Abandonment versus blocking in many-server queues: asymptotic optimality in the QED regime
Queueing Systems: Theory and Applications
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We develop a framework for asymptotic optimization of a queueing system. The motivation is the staffing problem of large call centers, which we have modeled as M/M/N queues with N , the number of agents, being large. Within our framework, we determine the asymptotically optimal staffing level N * that trades off agents' costs with service quality: the higher the latter, the more expensive is the former. As an alternative to this optimization, we also develop a constraint satisfaction approach where one chooses the least N * that adheres to a given constraint on waiting cost. Either way, the analysis gives rise to three regimes of operation: quality-driven, where the focus is on service quality; efficiency-driven, which emphasizes agents' costs; and a rationalized regime that balances, and in fact unifies, the other two. Numerical experiments reveal remarkable accuracy of our asymptotic approximations: over a wide range of parameters, from the very small to the extremely large, N * is exactly optimal, or it is accurate to within a single agent. We demonstrate the utility of our approach by revisiting the square-root safety staffing principle, which is a long-existing rule of thumb for staffing the M/M/N queue. In its simplest form, our rule is as follows: if c is the hourly cost of an agent, and a is the hourly cost of customers' delay, then N * = R + y* (a/c)vR , where R is the offered load, and y *(脗·) is a function that is easily computable.