An Integrated Approach for Shift Scheduling and Rostering Problems with Break Times for Inbound Call Centers
TL;DR: The results of the comprehensive computational study indicate that the constraint programming model runs more efficiently than the integer programming model for the rostering problem.
Abstract: It may be very difficult to achieve the optimal shift schedule in call centers which have highly uncertain and peaked demand during short time periods. Overlapping shift systems are usually designed for such cases. This paper studies shift scheduling and rostering problems for inbound call centers where overlapping shift systems are used. An integer programming model that determines which shifts to be opened and how many operators to be assigned to these shifts is proposed for the shift scheduling problem. For the rostering problem both integer programming and constraint programming models are developed to determine assignments of operators to all shifts, weekly days-off, and meal and relief break times of the operators. The proposed models are tested on real data supplied by an outsource call center and optimal results are found in an acceptable computation time. An improvement of 15% in the objective function compared to the current situation is observed with the proposed model for the shift scheduling problem. The computational performances of the proposed integer and constraint programming models for the rostering problem are compared using real data observed at a call center and simulated test instances. In addition, benchmark instances are used to compare our Constraint Programming (CP) approach with the existing models. The results of the comprehensive computational study indicate that the constraint programming model runs more efficiently than the integer programming model for the rostering problem. The originality of this research can be attributed to two contributions: (a) a model for shift scheduling problem and two models for rostering problem are presented in detail and compared using real data and (b) the rostering problem is considered as a task-resource allocation and considerably shorter computation times are obtained by modeling this new problem via CP.
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01 Jan 2015
TL;DR: In this article, a two-stage robust integer program with right-hand-side uncertainty is proposed to model the correlation of the demands in consecutive time slots. But the complexity issues of a Benders type reformulation are investigated and a branch-and-cut algorithm is devised.
Abstract: We study the shift scheduling problem in a multi-shift, flexible call center. Differently from previous approaches, the staffing levels ensuring the desired quality of service are considered uncertain, leading to a two-stage robust integer program with right-hand-side uncertainty. We show that, in our setting, modeling the correlation of the demands in consecutive time slots is easier than in other staffing approaches. The complexity issues of a Benders type reformulation are investigated and a branch-and-cut algorithm is devised. The approach can efficiently solve real-world problems from an Italian call center and effectively support managers decisions. In fact, we show that robust shifts have very similar costs to those evaluated by the traditional (deterministic) method while ensuring a higher level of protection against uncertainty.
22 citations
TL;DR: An enhanced artificial bee colony (EABC) algorithm to solve the workforce scheduling problem in call centres and the experimental results show that the proposed algorithm can achieve (sub-)optimal solutions for large-scale problems.
12 citations
TL;DR: In this paper, the authors consider three common scenarios: 1. Overstaffing: the workload level may be higher than expected, leading to long and irregular waiting times by the clients.
Abstract: These issues may increase with the significant levels of uncertainty entrenched in high workloads and peak demands at flexible working schedules set by three common scenarios: 1. Overstaffing: The workload level may be lower than expected; most employees become idle, resulting in high costs. 2. Understaffing: The workload level may be higher than expected, leading to long and irregular waiting times by the clients.
1 citations
01 Jan 2022
TL;DR: In this article , a mixed-integer linear programming (MILP) model was proposed to solve the problem of shift scheduling and rostering in a multi-skill call center.
Abstract: AbstractIn this paper, we consider the deterministic multi-skill employee call centre problem that considers staff scheduling and rostering. In this problem, we study the allocation of flexible shifts with the flexibility of starting the shift at the beginning of any hour of a day to both multi-skilled full-time employees and multi-skilled part-type employees who can handle the respective specific types of calls during the respective shift, thereby leading to combined problem of shift scheduling and rostering. In addition, we incorporate the days off scheduling and flexible break assignment in terms of the time of commencement of the break appropriately to every full-time employee and every part-time employee. Such real-life considerations demand the problem of shift scheduling and rostering to be solved in an integrated manner, and that too, by tracking every employee’s flexible shift assignment and rostering that depend upon the specific skill set of that employee to meet the demand of attending to specific types of calls (i.e. the construction of line of work over the planning horizon). We propose a mixed-integer linear programming (MILP) model with the objective of maximizing the total number of calls attended by the employees (i.e. maximizing the total number of tasks assigned). In our computational experiments, we generate many problem instances and present the results of the computational evaluation of the MILP model. We also present an illustration to bring out the impact of the flexible shift commencement in comparison to the fixed-shift scheduling with respect to employees.KeywordsCall centreFull-time and part-time staffSchedulingFlexible shiftDays offFlexible break assignmentSkill setRosteringMixed-integer linear programming
DOI•
09 Jun 2020
TL;DR: This research deals with the design, developing and testing of web-based duty scheduling system to schedule staff on a monthly basis so that a staff can have access to their duty roster irrespective of his/her location.
Abstract: This research deals with the design, developing and testing of web-based duty scheduling system to schedule staff on a monthly basis so that a staff can have access to their duty roster irrespective of his/her location. The Federal University of Agriculture Veterinary Teaching Hospital was used the case study for this work. A computer web based system called “Veterinary Duties Scheduler” was developed to this effect using PHP as the programming language, MySQL as the database and Unified Modelling Language (UML) as system design tool. After the new system was implemented, the results gotten showed clearly that staffs were now able to view their duty roster from any location by simply logging into the system using their staff-id and password. Therefore, the new system was able to solve most of the problems associated with the existing manual system of duty scheduling as witnessed in the case study.
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TL;DR: This work begins with a tutorial on how call centers function and proceed to survey academic research devoted to the management of their operations, which identifies important problems that have not been addressed and identifies promising directions for future research.
Abstract: Telephone call centers are an integral part of many businesses, and their economic role is significant and growing. They are also fascinating sociotechnical systems in which the behavior of customers and employees is closely intertwined with physical performance measures. In these environments traditional operational models are of great value--and at the same time fundamentally limited--in their ability to characterize system performance.We review the state of research on telephone call centers. We begin with a tutorial on how call centers function and proceed to survey academic research devoted to the management of their operations. We then outline important problems that have not been addressed and identify promising directions for future research.
1,415 citations
"An Integrated Approach for Shift Sc..." refers background in this paper
...Researchers generally use mathematical (queueing) models [2, 18, 77] for staffing subproblem....
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...[2], it is stated that labor costs are almost 70% of the total cost....
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...Themodels developed to calculate the number of essential workforces for the call centers are usually alternative of Erlang C calculations [2, 16, 18]....
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TL;DR: A review of staff scheduling and rostering, an area that has become increasingly important as business becomes more service oriented and cost conscious in a global environment, and the models and algorithms that have been reported in the literature for their solution.
1,238 citations
"An Integrated Approach for Shift Sc..." refers background in this paper
...There arise conflicting objectives when considering preferences of the employees, minimizing the costs, and meeting all the restrictions of the workplace [4]....
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...[4] present a review of workforce scheduling problems....
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TL;DR: An analysis of a unique record of call center operations that comprises a complete operational history of a small banking call center, call by call, over a full year is summarized.
Abstract: A call center is a service network in which agents provide telephone-based services. Customers who seek these services are delayed in tele-queues. This article summarizes an analysis of a unique record of call center operations. The data comprise a complete operational history of a small banking call center, call by call, over a full year. Taking the perspective of queueing theory, we decompose the service process into three fundamental components: arrivals, customer patience, and service durations. Each component involves different basic mathematical structures and requires a different style of statistical analysis. Some of the key empirical results are sketched, along with descriptions of the varied techniques required. Several statistical techniques are developed for analysis of the basic components. One of these techniques is a test that a point process is a Poisson process. Another involves estimation of the mean function in a nonparametric regression with lognormal errors. A new graphical technique ...
857 citations
TL;DR: A survey of the recent literature on call center operations management can be found in this article, where the authors identify a handful of broad themes for future investigation while also pointing out several very specific research opportunities.
Abstract: Call centers are an increasingly important part of today's business world, employing millions of agents across the globe and serving as a primary customer-facing channel for firms in many different industries. Call centers have been a fertile area for operations management researchers in several domains, including forecasting, capacity planning, queueing, and personnel scheduling. In addition, as telecommunications and information technology have advanced over the past several years, the operational challenges faced by call center managers have become more complicated. Issues associated with human resources management, sales, and marketing have also become increasingly relevant to call center operations and associated academic research.
In this paper, we provide a survey of the recent literature on call center operations management. Along with traditional research areas, we pay special attention to new management challenges that have been caused by emerging technologies, to behavioral issues associated with both call center agents and customers, and to the interface between call center operations and sales and marketing. We identify a handful of broad themes for future investigation while also pointing out several very specific research opportunities.
776 citations
"An Integrated Approach for Shift Sc..." refers background in this paper
...The first subproblem is about forecasting the work load and number of calls received within certain periods (usually 30minutes or 15minutes [6])....
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TL;DR: This paper presents a review of the literature on personnel scheduling problems and discusses the classification methods in former review papers, and evaluates the literature in the many fields that are related to either the problem setting or the technical features.
706 citations