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Access Type

Campus Access

Degree Program

Industrial Engineering & Operations Research

Degree Type

Master of Science in Industrial Engineering and Operations Research (M.S.I.E.O.R.)

Year Degree Awarded


Month Degree Awarded



Simulation, Discrete Event Simulation, Medicine, Emergency Department, Resource Management, Process Management, Optimization


Emergency Departments (ED) in the US are in crisis. In 2004 between 40 and 50% of the US hospitals experienced crowding. Crowding negatively affects the quality and access of emergency care. Optimally managing the present resources in EDs and finding ways to reduce patient length of stay is critical to improving patient care in EDs. We use computer simulation modeling of patient flow in an ED (i.e. discrete event simulation) to study the impact of 1) resource management and profit optimization, 2) process changes, and 3) task prioritization on patient length of stay. Our model of patient flow, ED with multiple Acuities (EDWA), consists of a five-fold process of emergency care which represents five different types of patients. This model assigns each patient to an individual doctor and allows patient treatment process to proceed simultaneously or sequentially with other activities. The results show an increase in the need for resources with an increase in variability; the dependency of the optimal resource mix on the objective we want to optimize; and the relationship between quality of emergency care and profitability. Further, our findings imply that bedside registration (a commonly recommended process change in EDs) should only be implemented when emergency department beds are free.

First Advisor

Hari J. Balasubramanian

Second Advisor

Philip A. Henneman