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Call Center Staffing: Service-Level Constraints and Index Priorities

Author

Listed:
  • Seung Bum Soh

    (College of Business Administration, Sejong University, Seoul, South Korea)

  • Itai Gurvich

    (School of Operations Research and Information Engineering, Cornell Tech, New York, New York 10011)

Abstract

Call centers attribute different values to different customer segments. These values are reflected in quality-of-service targets. The prevalent target service factor (TSF) formulation requires, for example, that 80% of VIP customers wait less than 20 seconds while setting the target to 30 seconds for non-VIP customers. The call center must determine the staffing level together with a prioritization rule that meets these targets at minimal cost. In practice, because of the underlying complexity of these systems, the prioritization rule is often selected in a heuristic manner rather than being systematically optimized. When considering the universe of prioritization policies, index rules provide a customizable and easy to define heuristic and for this reason are implemented in various call center software packages. We use the TSF formulation as a stepping stone toward a better understanding of index rules. We first construct an asymptotically optimal solution for the TSF problem. The prioritization component of our solution is a tracking policy rather than an index rule. We prove that despite index rules’ significant flexibility, no instance of these prioritization rules is optimal for the TSF problem. The suboptimality of index rules follows from an essential characteristic of these: restricting attention to index rules (as is heuristically done in practice) is asymptotically equivalent to requiring that a VIP customer always waits less than a regular (non-VIP) customer who arrives at the same time. This, in particular, implies that the use of index rules in practice can be rationalized if (and only if) the manager requires such strong differentiation.

Suggested Citation

  • Seung Bum Soh & Itai Gurvich, 2017. "Call Center Staffing: Service-Level Constraints and Index Priorities," Operations Research, INFORMS, vol. 65(2), pages 537-555, April.
  • Handle: RePEc:inm:oropre:v:65:y:2017:i:2:p:537-555
    DOI: 10.1287/opre.2016.1532
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    References listed on IDEAS

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    1. Shlomo Halfin & Ward Whitt, 1981. "Heavy-Traffic Limits for Queues with Many Exponential Servers," Operations Research, INFORMS, vol. 29(3), pages 567-588, June.
    2. Mor Armony & Avishai Mandelbaum, 2011. "Routing and Staffing in Large-Scale Service Systems: The Case of Homogeneous Impatient Customers and Heterogeneous Servers," Operations Research, INFORMS, vol. 59(1), pages 50-65, February.
    3. Itay Gurvich & Mor Armony & Avishai Mandelbaum, 2008. "Service-Level Differentiation in Call Centers with Fully Flexible Servers," Management Science, INFORMS, vol. 54(2), pages 279-294, February.
    4. Sem Borst & Avi Mandelbaum & Martin I. Reiman, 2004. "Dimensioning Large Call Centers," Operations Research, INFORMS, vol. 52(1), pages 17-34, February.
    5. Avishai Mandelbaum & Alexander L. Stolyar, 2004. "Scheduling Flexible Servers with Convex Delay Costs: Heavy-Traffic Optimality of the Generalized cμ-Rule," Operations Research, INFORMS, vol. 52(6), pages 836-855, December.
    6. Wyean Chan & Ger Koole & Pierre L'Ecuyer, 2014. "Dynamic Call Center Routing Policies Using Call Waiting and Agent Idle Times," Manufacturing & Service Operations Management, INFORMS, vol. 16(4), pages 544-560, October.
    7. Itai Gurvich & Ward Whitt, 2010. "Service-Level Differentiation in Many-Server Service Systems via Queue-Ratio Routing," Operations Research, INFORMS, vol. 58(2), pages 316-328, April.
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