Decision Sciences and MIS

Past Seminars

This talk illustrates capabilities in Mathematica 11 and other Wolfram technologies that are directly applicable for use in teaching and research on campus.

Murat Kurt
Senior Scientist of Outcomes Research, Predictive and Economic Modeling
Merck & Co, Inc.

Yunan Liu, NC State University

Abstract: Queueing theory is a field driven by applications. But unfortunately, there still remains a large gap between tractable theoretical studies and practical applications, such as call centers and health care systems, which have many realistic features (e.g., time-varying arrivals, customer abandonment, non-exponential distributions, and complicated network structures). In response to the challenge, we study a general G_t/GI/s_t+GI queueing model, which has a non-stationary non-Poisson arrival process (the G_t), non-exponential service times (the first GI), and allows customer abandonment according to a non-exponential patience distribution (the +GI). To bridge the gap between mathematical tractability and model applicability, we develop fundamental principles and optimal control policies for such a general queueing model.
Analytic formulas are developed to set the time-dependent number of servers in order to stabilize important service-level indicators, including: mean customer delay, probability of abandonment, and tail probability of delay (TPoD). Taking the TPoD for example: for any delay target w > 0 and probability target 0 < alpha < 1, we determine appropriate time-dependent staffing levels (the s_t) so that the time-varying probability that the waiting time exceeds a maximum acceptable value w is stabilized at alpha at all times. In addition, effective approximating formulas are provided for other important performance functions such as the probabilities of delay and abandonment, and the means of delay and queue length. Many-server heavy-traffic limit theorems in the efficiency-driven regime are developed to show that (i) the proposed staffing function achieves the goal asymptotically as the scale increases, and (ii) the proposed approximating formulas for other performance measures are asymptotically accurate as the scale increases. Extensive simulations show that both the staffing functions and the performance approximations are effective, even for smaller systems having an average of 3 servers.

U.S. hospitals join GPOs for procurement cost savings. It is generally believed that GPOs lower costs through demand aggregation. Until recently hospitals purchasing supplies from a GPO vendor had to pay a GPO-negotiated price. The novel practice of custom contracting allows GPO member hospital to negotiate with GPO vendors to improve on the GPO negotiated prices. Hospital procurement departments have welcomed this practice, lauding the opportunity to further lower hospital costs. In this paper, we use economic modeling to investigate the practice of custom contracting. We develop a game-theoretic model treating as endogenous the pricing and negotiations decisions of the GPO vendor and of member hospitals. We show why – counter to the hospital industry’s expectations – expected purchase prices will not decrease with the introduction of custom contracting. The practice benefits GPO vendors at the expense of the member hospitals.

Decision Sciences Department Seminar Series
The Department of Decision Sciences invites you to attend
Estimation of Downside Risks in Project Portfolio Selection
Speaker: Janne Kettunen, Assistant Professor, George Washington University

Title: “The Case for 3rd Party Supply Chain Coordination”
Presenter: Kurt Masten, doctoral student in decision sciences
Title: “An Economic Order Quantity Model for Items Experiencing Failure in Storage”
Presenter: Mikhail Sher, doctoral student in decision sciences

The Department of Decision Sciences invites you to attend
Informing and Personalizing the Response to Inpatient Physiological Deterioration Using Early Warning Scores
Speaker: Muge Capan, Ph.D., Research Investigator at Value Institute

The Department of Decision Sciences invites you to attend
Multi-Echelon Inventory Optimization under the Threat of Disruptions
Speaker: Larry Snyder, Ph.D., Associate Professor at Lehigh University

The Department of Decision Sciences invites you to attend
Dynamic Pricing and Replenishment with Customer Upgrades

A Structural Analysis of Standard and Fixed-Charge Transportation Problems
Speaker: Krzysztof Kowalski, Senior Engineer, Connecticut Department of Transportation
Friday, May 16th, 2014, 1 – 2 p.m.