Presentation Title: Service-level differentiation in large-scale service systems

Abstract: Motivated by telephone call centers, we study the problem of service-level differentiation in largescale service systems with multiple customer classes and multiple agent pools. Call Centers usually specify their operational objectives through the x-y service-level (SL) constraint, which stipulates that x% of the calls should be answered within y seconds. Typically, service-level differentiation is imposed through different SL objectives for different customer classes. In order to achieve these constraints a Call-Center needs to determine the types of agents that will be used (Design), the number of agents of each type (Staffing) and the real-time control to be used (Routing). We propose a solution based on a family of routing controls called Fixed-Queue-Ratio (FQR) rules. In many settings, FQR allows us to solve the combined Design-Staffing-and-Routing problem in a nearly optimal way. Our analysis also establishes a diminishing-returns property of flexibility by showing that,under FQR, very moderate cross-training is sufficient to make the call center work as efficiently as a single-pool system. This is joint work with Ward Whitt.

Education
2004-2008 Graduate School of Business, Columbia University, New York.
PhD in Decisions, Risk and Operations
Dissertation: "Staffing and Control of Many-Server Service Systems". Principal Adviser: Ward Whitt; Co-Advisers: Mor Armony, Costis Maglaras and Assaf Zeevi.

2002-2004 Technion