Apologies for cross-posting.
Dear Colleagues and Students,
INFORMS Service Science Online Forum Series - Episode 13 features our next speaker Prof. Hossein Abouee Mehrizi (Department of Management Science and Engineering, University of Waterloo), who will present his research on the efficiency-equity trade-off in service systems with differentiated demand: whether prioritizing urgent customers must come at the expense of equity, and how priority policies can deliver substantial gains in one objective with only marginal sacrifices in the other, with important implications for service operations, healthcare delivery, and customer welfare.
See you online for Episode 13 via this Zoom link, where queueing theory, equity, and service operations meet!
Speaker: Prof. Hossein Abouee Mehrizi (Department of Management Science and Engineering, University of Waterloo)
Moderator: Prof. Mustafa Akan, Carnegie Mellon University
Topic: Equity vs. Efficiency in Service Systems with Differentiated Demand
Abstract: In service systems, the pursuit of efficiency by prioritizing certain groups often raises equity concerns for those not prioritized. We study the efficiency-equity trade-off in a queueing system with two heterogeneous customer classes. We first consider mandatory services that customers do not balk at. Among all work-conserving, non-preemptive priority policies, we examine two objectives: an efficient (i.e., utilitarian) objective that minimizes the system's overall expected disutility and is attained by the well-known cμ-rule, and an equitable (i.e., egalitarian) objective that minimizes the maximum expected disutility of individual customers. We characterize the optimal equitable policy and show that it strictly prioritizes urgent customers at low utilization but, beyond a threshold, tempers priority across classes. This suggests that equity is congestion-sensitive rather than intrinsically anti-efficient. We then quantify the efficiency-equity trade-off through the price of equity (PEQ), the relative efficiency loss under the equitable policy, and the price of efficiency (PEF), the relative equity loss under the efficient policy. We fully characterize the effects of congestion and customer heterogeneity on PEQ and PEF and derive tight analytical bounds. Our analysis identifies broad parameter regimes in which either the efficient or the equitable policy performs well on both dimensions, implying only a limited trade-off. When the trade-off remains nontrivial, we establish a balanced-loss policy whose worst relative loss is strictly smaller than that under either single-objective optimum. We confirm the robustness of the main insights in two extensions. First, when customers endogenously balk, customer coverage (i.e., the fraction of potential customers served) becomes an additional performance dimension, introducing diversity concerns that we study through lexicographic objectives. Second, motivated by risk-averse customers, we analyze a variance-based equity objective. Overall, our results challenge the perception that efficiency and equity(-diversity) lie at opposite ends of the spectrum, showing that substantial improvements in one can be achieved with only marginal sacrifices in the other.
Time: August 24, 2026, Monday, 10:00 AM–11:00 AM Eastern Time
Zoom link: https://cornell.zoom.us/j/93641303385?pwd=DZaPz33oEe67U029UxJB45JybA165f.1
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For more information, see our website https://sites.google.com/view/service-science-online-forum/, and our YouTube Channel https://www.youtube.com/playlist?list=PLCn8oCTLj5JEeIiA3_ATZp8gtlkWJCRpO. Join our mail list to get the information about new episodes of Service Science Online Forum: https://forms.gle/k5L52JZbW8kpLYrf7.
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Renyu Zhang
Professor
The Chinese University of Hong Kong
Hong Kong
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