Designing a Call Center with Impatient Customers

@article{Garnett2002DesigningAC,
  title={Designing a Call Center with Impatient Customers},
  author={O. Garnett and Avishai Mandelbaum and Martin I. Reiman},
  journal={Manuf. Serv. Oper. Manag.},
  year={2002},
  volume={4},
  pages={208-227}
}
The most common model to support workforce management of telephone call centers is theM/ M/ N/ B model, in particular its special casesM/ M/ N (Erlang C, which models out busy signals) andM/ M/ N/ N (Erlang B, disallowing waiting). All of these models lack a central prevalent feature, namely, that impatient customers might decide to leave (abandon) before their service begins.In this paper, we analyze the simplest abandonment model, in which customers' patience is exponentially distributed and… 
Application of queueing models with abandonment for Call Center congestion analysis
TLDR
It is shown that the M/M/c+G analytical queueing models with abandonment, with patience time represented by generic distributions (particularly mixed distributions), are more effective than the M-M-c+M analytical queues with abandonment with Exponential patience, commonly used to evaluate congestion problems in Call Centers and support sizing and operational decisions in these systems.
Designing a call center with an IVR (Interactive Voice Response)
TLDR
A Markovian model for a call center with an IVR is studied, which approximate operational performance measures, such as the probability for a busy signal and the average wait time for an agent, in an asymptotic regime known as QED or the Halfin–Whitt regime, which accommodates moderate to large call centers.
Engineering Solution of a Basic Call-Center Model
  • W. Whitt
  • Computer Science, Engineering
    Manag. Sci.
  • 2005
An algorithm is developed to rapidly compute approximations for all the standard steady-state performance measures in the basic call-center queueing modelM/GI/s/r+GI, which has a Poisson arrival
Call Centers with Impatient Customers: Many-Server Asymptotics of the M/M/n + G Queue
TLDR
Empirical findings have demonstrated a robust linear relation between the fraction abandoning and average wait, and the QED and QD formulae provide excellent approximation for exact M/M/n + G performance measures.
Call center operation model as a MAP/PH/N/R−N system with impatient customers
TLDR
An algorithm for finding the stationary distribution of system states and derive formulas for basic performance characteristics are given and Laplace-Stieltjes transforms for sojourn and waiting times are found.
Staffing Many-Server Queues with Impatient Customers: Constraint Satisfaction in Call Centers
TLDR
This work considers a constraint satisfaction problem, where one chooses the minimal staffing level n that adheres to a given cost constraint, and proposes a new ED + QED operational regime that enables QED tuning of the ED regime.
Adaptive Behavior of Impatient Customers in Tele-Queues: Theory and Empirical Support
TLDR
This paper addresses the modeling and analysis of abandonments from a queue that is invisible to its occupants, and proposes an M/M/m-based model that incorporates adaptive customer behavior and establishes the existence and uniqueness of the operating point in steady state.
On first-come, first-served queues with two classes of impatient customers
TLDR
A virtual waiting time process is introduced where the service times of customers who will eventually abandon the system are not considered and the performance measures of the M/M/k + M system serve as good approximations of the system based on real data.
Many-server queues with customer abandonment: A survey of diffusion and fluid approximations
TLDR
This survey paper focuses on G / GI / n + GI parallel-server queues that serve as a building block to model call center operations and results include the performance insensitivity to patience time distributions and diffusion and fluid approximate models as practical tools for performance analysis.
The impact of retrials on call center performance
TLDR
This paper models a call center as a Markovian queue with multiple servers, where customer balking, impatience, and retrials are modeled explicitly, and explores the retrial phenomenon for a real call center.
...
1
2
3
4
5
...

References

SHOWING 1-10 OF 50 REFERENCES
Adaptive Behavior of Impatient Customers in Tele-Queues: Theory and Empirical Support
TLDR
This paper addresses the modeling and analysis of abandonments from a queue that is invisible to its occupants, and proposes an M/M/m-based model that incorporates adaptive customer behavior and establishes the existence and uniqueness of the operating point in steady state.
Dimensioning Large Call Centers
TLDR
A framework for asymptotic optimization of a queueing system based on the staffing problem of call centers with 100's of agents is developed, and the square-root safety staffing principle is revisited, which is a long-existing rule-of-thumb for staffing the M/M/N queue.
On the M(n)/M(n)/s Queue with Impatient Calls
TLDR
Numerical results are given for the case of maximal waiting times as the minimum of constant and exponentially distributed times of an automatic call distributor system (ACD system) of finite capacity with outbound and impatient inbound calls.
A model for rational abandonments from invisible queues
TLDR
This work proposes a model for abandonments from a queue, due to excessive wait, assuming that waiting customers act rationally but without being able to observe the queue length, and shows that a unique equilibrium exists, in which rational abandonments can occur only upon arrival.
On a Two-Queue Priority System with Impatience and its Application to a Call Center*
We consider an s-server priority system with a protected and an unprotected queue. The arrival rates at the queues and the service rate may depend on the number n of customers being in service or in
Queuing with reneging and multiple heterogeneous servers
TLDR
A comparison is made of a heterogeneous system with an equivalent homogeneous system and density functions and mean values of waiting times in queue for those who are served, those who renege, and all who enter are compared.
Modeling the IRS Telephone Taxpayer Information System
TLDR
A simulation-based model was built to test various allocation policies for deploying IRS resources, and the feasibility of modeling a typical IRS location as a multiserver loss/delay queue with retrial and reneging was shown.
Strong approximations for Markovian service networks
TLDR
This work develops limit theorems for a large class of stochastic service network models where parameters like arrival and service rates, routing topologies for the network, and the number of servers at a given node are all functions of time as well as the current state of the system.
Understanding the Efficiency of Multi-Server Service Systems
TLDR
This analysis develops simple approximations for the mean steady- state waiting time and the full steady-state waiting-time distribution and shows how increased variability in the arrival and service processes tends to reduce server utilization with a given grade of service.
Estimation of a caller retrial rate for a telephone information system
TLDR
The thrust of this current study was to develop an accurate statistical method for providing a more objective formula for this true demand, which turns out to be equivalent to estimating the probability of retrial by blocked and abandoned callers.
...
1
2
3
4
5
...