Global Pervasive Computational Epidemiology Seminar Series
Date/time: Thursday, July 14, 11:30am – 12:30pm Eastern (USA)
Topic: Shift, Scale and Restart Smaller Models to Estimate Larger Ones: Agent- based Simulators for Covid Modelling
Speaker: Sandeep Juneja
Zoom link: https://virginia.zoom.us/j/92700002677?pwd=Zi8vQ21TUHpBQVYxQXFpaTZPY2FNdz09
Abstract: Agent-based simulators are a popular epidemiological modelling tool to study the impact of various non- pharmaceutical interventions in managing an evolving pandemic. They provide the flexibility to accurately model a heterogeneous population with time and location varying, person specific interactions. To accurately model detailed behaviour, typically each person is separately modelled. This however, may make computational time prohibitive when the region population is large and when time horizons involved are large. We observe that simply considering a smaller aggregate model and scaling up the output leads to inaccuracies. In this talk we primarily focus on the COVID-19 pandemic and dig deeper into the underlying probabilistic structure of an associated agent based simulator (ABS) to arrive at modifications that allow smaller models to give accurate statistics for larger models. We exploit the observations that in the initial disease spread phase, the starting infections behave like a branching process. Further, later once enough people have been infected, the infected population closely follows its mean field approximation. We build upon these insights to develop a shifted, scaled and restart version of the simulator that accurately evaluates the ABS’s performance using a much smaller model while essentially eliminating the bias that otherwise arises from smaller models.
Speaker Bio: Sandeep is a senior professor at the School of Technology and Computer Science in Tata Institute of Fundamental Research in Mumbai. His research interests lie in applied probability including in sequential learning, financial mathematics, Monte Carlo methods, and game theoretic analysis of queues. Lately, he has been involved in modelling Covid-19 spread in Mumbai, and in mathematics of agent-based simulation models. Sandeep received his B. Tech. from IIT Delhi and Masters in Statistics and PhD in Operations Research from Stanford University. He is currently on the editorial board of Stochastic Systems. Earlier he has been on editorial boards of Mathematics of Operations Research, Management Science and ACM TOMACS.