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Saturday, November 7, 2020

Data-Driven Mobility Models for COVID-19 Simulation

John Pesavento, Andy Chen, Rayan Yu, Joon-Seok Kim, Hamdi Kavak, Taylor Anderson, Andreas Züfle


Agent-based models (ABM) play a prominent role in guiding critical decision-making and supporting the development of effective policies for better urban resilience and response to the COVID-19 pandemic. However, many ABMs lack realistic representations of human mobility, a key process that leads to physical interaction and subsequent spread of disease. Therefore, we propose the application of Latent Dirichlet Allocation (LDA), a topic modeling technique, to foot-traffic data to develop a realistic model of human mobility in an ABM that simulates the spread of COVID-19. In our novel approach, LDA treats POIs as “words” and agent home census block groups (CBGs) as “documents” to extract “topics” of POIs that frequently appear together in CBG visits. These topics allow us to simulate agent mobility based on the LDA topic distribution of their home CBG. We compare the LDA based mobility model with competitor approaches including a naive mobility model that assumes visits to POIs are random. We find that the naive mobility model is unable to facilitate the spread of COVID-19 at all. Using the LDA informed mobility model, we simulate the spread of COVID-19 and test the effect of changes to the number of topics, various parameters, and public health interventions. By examining the simulated number of cases over time, we find that the number of topics does indeed impact disease spread dynamics, but only in terms of the outbreak's timing. Further analysis of simulation results is needed to better understand the impact of topics on simulated COVID-19 spread. This study contributes to strengthening human mobility representations in ABMs of disease spread.

Three promising high school students, John Pesavento, Andy Chen, and Rayan Yu, presented our recent research "Data-Driven Mobility Models for COVID-19 Simulation" at the 3rd ACM SIGSPATIAL Workshop on Advances in Resilient and Intelligent Cities (ARIC 2020)! I am a witness to their hard work during Aspiring Scientists Summer Internship Program (ASSIP). These dilligent students were mentored by Dr. Andreas Züfle and Dr. Hamdi Kavak and co-mentored by Dr. Anderson Taylor and myself. The presentation at ARIC 2020 was very clear. Well done!

You can check out interactive heatmaps and more information in John Peasavento's GitHub Page. This research is supported by National Science Foundation and by the Aspiring Scientists Summer Internship Program (ASSIP) at George Mason University.

J. Pesavento, A. Chen, R. Yu, J.-S. Kim, H. Kavak, T. Anderson, and A. Züfle, “Data Driven Mobility Models for COVID-19 Simulation,” In Proceedings of the 3rd ACM SIGSPATIAL Workshop on Advances in Resilient and Intelligent Cities (ARIC 2020), November 2020, pp. 29-38 

Tuesday, November 3, 2020

COVID-19 Ensemble Models Using Representative Clustering

Joon-Seok Kim, Hamdi Kavak, Andreas Züfle, Taylor Anderson


In response to the COVID-19 pandemic, there have been various attempts to develop realistic models to both predict the spread of the disease and evaluate policy measures aimed at mitigation. Different models that operate under different parameters and assumptions produce radically different predictions, creating confusion among policy-makers and the general population and limiting the usefulness of the models. This newsletter article proposes a novel ensemble modeling approach that uses representative clustering to identify where existing model predictions of COVID-19 spread agree and unify these predictions into a smaller set of predictions. The proposed ensemble prediction approach is composed of the following stages: (1) the selection of the ensemble components, (2) the imputation of missing predictions for each component, and (3) representative clustering in application to time-series data to determine the degree of agreement between simulation predictions. The results of the proposed approach will produce a set of ensemble model predictions that identify where simulation results converge so that policy-makers and the general public are informed with more comprehensive predictions and the uncertainty among them. 

Courtesy of NSFwe shared our vision at the 1st ACM SIGSPATIAL International Workshop on Modeling and Understanding the Spread of COVID-19 presented by Dr. Hamdi Kavak. 

J-S. Kim, H. Kavak, A. Züfle, T. Anderson, “COVID-19 Ensemble Models Using Representative Clustering,” SIGSPATIAL Special, July 2020, Volume 12, Issue 2, pp 33-41