Prof. Chung Piaw Teo
National University of Singapore
Talk:
Scheduling Arrivals to a Stochastic Service Delivery System using Copositive Cones
Abstract:
We develop a convex programming approach to the appointment system design problem in a single server facility, using a (stochastic) network flow model to capture the waiting time performance measure of each patient in the system. We solve a robust min-max problem, using a representative ''worst case" distribution matching the prescribed means and covariance estimates of the service durations of the patients, to determine the optimal schedule. Using this approach, the scheduling problem (finding the arrival time of the patients) can be determined by solving a semi-definite programming relaxation.Our analysis and numerical results yield several interesting insights on the nature of the optimal appointment system design - the scheduling decisions obtained by planning against the ``worst case" distribution performed exceedingly well even for several other distributions with the same mean and covariance parameters. Furthermore, for multi-class appointment system, if patients with higher variability are to be seen first before patients with lower variability, the optimal schedule generally exhibits 'Bailey's Rule + break' structure, with first few patients coming ``close together" at the beginning, and a higher than usual interval for the last patient in the first class. Our analysis also reveals an interesting characteristic of the optimal appointment system - except for the first and last few slots with zero consultation interval allocated to them, the chances of waiting for consultation service is identical for patients choosing all other slots in the system! This is joint work with Qingxia Kong (NUS), Zhichao Zheng (NUS), and Chung Yee Lee (HKUST).
Biography:
TEO Chung Piaw is the Acting Deputy Dean at the NUS Business School, National University of Singapore, and a Professor in the Department of Decision Sciences in NUS. Prior to his recent appointment, he was Vice-Dean of the Research & PhD Program as well as Chair of the PhD Committee in the School. He received his PhD in Operations Research from Massachusetts Institute of Technology, Cambridge, MA, and his BSc (Hons) degree in Mathematics from the National University of Singapore. He was an Eschbach Scholar in Northwestern University (US), Professor in Sungkyunkwan Graduate School of Business (Korea), and a Distinguished Visiting Professor in YuanZe University (Taiwan).His research interests lie in service and manufacturing flexibility, discrete optimization, ports container operations, matching and exchange, and healthcare. He is currently the associate editor of several international journals (Operations Research, Management Science, and IIE Transactions etc.), and has served on several international committee such as the Chair of the Nicholson Paper Competition (US), member of the Fudan Prize Committee on Outstanding Contribution to Management (China), and the Hong Kong PhD Fellowship Scheme Selection Panel.
