Joshua M. Epstein
Professor of Epidemiology
Dr. Joshua M. Epstein’s research focuses on modeling complex social, economic, and biological systems using agent-based computational models and nonlinear dynamic systems.
Dr. Epstein has extensive experience in mathematical and computational modeling of biomedical and social dynamics at all scales - from local to national to planetary. He pioneered the technique of agent-based computational modeling and has applied it to problems in social, behavioral, and biomedical science by modeling economic dynamics, patterns of civil violence, the evolution of norms, the computational reconstruction of the ancient civilization of the Anasazi, and the epidemiology of the 2009 Swine Flu pandemic, smallpox, HIV, and Ebola. To design evacuation and longer-term adaptation to climate change, he combined computational fluid dynamics (i.e. toxic plume dispersion) with human behavior to create a stunning 3D artificial Los Angeles. In response to Zika and in collaboration with colleagues and the New York Department of Health and Mental Hygiene, Dr. Epstein has developed an artificial New York City to be applied to urban health policy challenges. His work has had a profound influence on emerging infectious diseases, bioterrorism, and the nascent field of disaster health, which is being developed under Presidential Directive (I-ISPD-21).
Dr. Epstein is the Director of the Agent-Based Modeling Lab, which works with large-scale epidemic models and cognitively plausible agents in order to produce a transformative synthesis for global public health modeling through the generative social science approach.
Previously, Dr. Epstein has worked at John Hopkins University, Princeton University, University of Pittsburgh, George Mason University, the Sante Fe Institute, and the Brookings Institution. He has also authored and co-authored seminal books, including Growing Artificial Societies: Social Science from the Bottom Up; Generative Social Science: Studies in Agent-Based Computational Modeling; and Agent_Zero: Toward Neurocognitive Foundations for Generative Social Science.
BA, Independent Scholar with Thesis in Political Economy, Amherst College, Amherst, MAPhD, Political Science (Specialization: Security Studies, Communist Studies, and Economics), Massachusetts Institute of Technology, Cambridge, MA
Honorary Doctorate of Science, Amherst College (2010)Director’s Pioneer Award, National Institutes of Health (2008)Rockefeller Foundation International Relations Fellowship (1984)Council on Foreign Relations International Affairs Fellowship (1983)Ford Foundation Dual Expertise Fellowship in Soviet/East European Area Studies and International Security/Arms Control (1981)Institute for the Study of World Politics Fellowship (1981)
Agent-Based ModelingApplied EconomicsCost AnalysisDisaster HealthEpidemiologyHealth EconomicsInfectious DiseasesMathematical and Computational ModelingModeling Social and Behavioral DynamicsNew York Department of Health and Mental HygienePublic Health SystemsUrban HealthUrban InformaticsUrban Science
Advancing Agent_ZeroEpstein, J., & Chelen, J. In Complexity and Evolution: Toward a New Synthesis for Economics.
Social conformity despite individual preferences for distinctivenessSmaldino, P. E., & Epstein, J. M.
Journal titleRoyal Society Open Science
Issue3We demonstrate that individual behaviours directed at the attainment of distinctiveness can in fact produce complete social conformity. We thus offer an unexpected generative mechanism for this central social phenomenon. Specifically, we establish that agents who have fixed needs to be distinct and adapt their positions to achieve distinctiveness goals, can nevertheless self-organize to a limiting state of absolute conformity. This seemingly paradoxical result is deduced formally from a small number of natural assumptions and is then explored at length computationally. Interesting departures from this conformity equilibrium are also possible, including divergence in positions. The effect of extremist minorities on these dynamics is discussed. A simple extension is then introduced, which allows the model to generate and maintain social diversity, including multimodal distinctiveness distributions. The paper contributes formal definitions, analytical deductions and counterintuitive findings to the literature on individual distinctiveness and social conformity.
Agent_Zero: Toward Neurocognitive Foundations for Generative Social ScienceEpstein, J. M.
Volume9781400848256The Final Volume of the Groundbreaking Trilogy on Agent-Based Modeling. In this pioneering synthesis, Joshua Epstein introduces a new theoretical entity: Agent_Zero. This software individual, or "agent," is endowed with distinct emotional/affective, cognitive/deliberative, and social modules. Grounded in contemporary neuroscience, these internal components interact to generate observed, often far-from-rational, individual behavior. When multiple agents of this new type move and interact spatially, they collectively generate an astonishing range of dynamics spanning the fields of social conflict, psychology, public health, law, network science, and economics. Epstein weaves a computational tapestry with threads from Plato, Hume, Darwin, Pavlov, Smith, Tolstoy, Marx, James, and Dostoevsky, among others. This transformative synthesis of social philosophy, cognitive neuroscience, and agent-based modeling will fascinate scholars and students of every stripe. Epstein's computer programs are provided in the book or on its Princeton University Press website, along with movies of his "computational parables." Agent_Zero is a signal departure in what it includes (e.g., a new synthesis of neurally grounded internal modules), what it eschews (e.g., standard behavioral imitation), the phenomena it generates (from genocide to financial panic), and the modeling arsenal it offers the scientific community. For generative social science, Agent_Zero presents a groundbreaking vision and the tools to realize it.
Modeling the regional spread and control of vancomycin-resistant enterococciLee, B. Y., Yilmaz, S. L., Wong, K. F., Bartsch, S. M., Eubank, S., Song, Y., Avery, T. R., Christie, R., Brown, S. T., Epstein, J. M., Parker, J. I., & Huang, S. S.
Journal titleAmerican Journal of Infection Control
Page(s)668-673Background: Because patients can remain colonized with vancomycin-resistant enterococci (VRE) for long periods of time, VRE may spread from one health care facility to another. Methods: Using the Regional Healthcare Ecosystem Analyst, an agent-based model of patient flow among all Orange County, California, hospitals and communities, we quantified the degree and speed at which changes in VRE colonization prevalence in a hospital may affect prevalence in other Orange County hospitals. Results: A sustained 10% increase in VRE colonization prevalence in any 1 hospital caused a 2.8% (none to 62%) average relative increase in VRE prevalence in all other hospitals. Effects took from 1.5 to >10 years to fully manifest. Larger hospitals tended to have greater affect on other hospitals. Conclusions: When monitoring and controlling VRE, decision makers may want to account for regional effects. Knowing a hospital's connections with other health care facilities via patient sharing can help determine which hospitals to include in a surveillance or control program.
Agent-based computational models and generative social scienceEpstein, J. M. In Generative Social Science.
Coordination in transient social networksAxtell, R. L., & Epstein, J. M. In Generative Social Science: An agent-based computational model of the timing of retirement.
Generative social science: Studies in agent-based computational modelingEpstein, J. M.
Publication year2012Agent-based computational modeling is changing the face of social science. In Generative Social Science, Joshua Epstein argues that this powerful, novel technique permits the social sciences to meet a fundamentally new standard of explanation, in which one "grows" the phenomenon of interest in an artificial society of interacting agents: heterogeneous, boundedly rational actors, represented as mathematical or software objects. After elaborating this notion of generative explanation in a pair of overarching foundational chapters, Epstein illustrates it with examples chosen from such far-flung fields as archaeology, civil conflict, the evolution of norms, epidemiology, retirement economics, spatial games, and organizational adaptation. In elegant chapter preludes, he explains how these widely diverse modeling studies support his sweeping case for generative explanation. This book represents a powerful consolidation of Epstein's interdisciplinary research activities in the decade since the publication of his and Robert Axtell's landmark volume, Growing Artificial Societies. Beautifully illustrated, Generative Social Science includes a CD that contains animated movies of core model runs, and programs allowing users to easily change assumptions and explore models, making it an invaluable text for courses in modeling at all levels.
Growing adaptive organizationsEpstein, J. M. In Generative Social Science: An agent-based computational approach.
Learning to be thoughtlessEpstein, J. M. In Generative Social Science: Social norms and individual computation.
Modeling civil violenceEpstein, J. M. In Generative Social Science: An agent-based computational approach.
Non-explanatory equilibriaEpstein, J. M., & Hammond, R. A. In Generative Social Science: An extremely simple game with (mostly) unattainable fixed points.
Population growth and collapse in a multiagent model of the kayenta anasazi in long house valleyAxtell, R. L., Epstein, J. M., Dean, J. S., Gumerman, G. J., Swedlund, A. C., Harburger, J., Chakravarty, S., Hammond, R., Parker, J., & Parker, M. In Generative Social Science.
Remarks on the foundations of agent-based generative social scienceEpstein, J. M. In Generative Social Science.
The emergence of classes in a multi-agent bargaining modelAxtell, R. L., Epstein, J. M., & Young, H. P. In Generative Social Science.
The evolution of social behavior in the prehistoric American southwestGumerman, G. J., Swedlund, A. C., Dean, J. S., & Epstein, J. M. In Generative Social Science.
Toward a containment strategy for smallpox bioterrorEpstein, J. M., Cummings, D. A., Chakravarty, S., Singha, R. M., & Burke, D. S. In Generative Social Science: An individual-based computational approach.
Understanding anasazi culture change through agent-based modelingDean, J. S., Gumerman, G. J., Epstein, J. M., Axtell, R. I., Swedlund, A. C., Parker, M. T., & Mccarroll, S. In Generative Social Science.
Zones of cooperation in demographic prisoner's dilemmaEpstein, J. M. In Generative Social Science.
A distributed platform for global-scale agent-based models of disease transmissionParker, J., & Epstein, J. M.
Journal titleACM Transactions on Modeling and Computer Simulation
Issue1The Global-Scale Agent Model (GSAM) is presented. The GSAM is a high-performance distributed platform for agent-based epidemic modeling capable of simulating a disease outbreak in a population of several billion agents. It is unprecedented in its scale, its speed, and its use of Java. Solutions to multiple challenges inherent in distributing massive agent-based models are presented. Communication, synchronization, and memory usage are among the topics covered in detail. The memory usage discussion is Java specific. However, the communication and synchronization discussions apply broadly. We provide benchmarks illustrating the GSAM's speed and scalability.
Combining computational fluid dynamics and agent-based modeling: A new approach to evacuation planningEpstein, J. M., Pankajakshan, R., & Hammond, R. A.
Journal titlePLoS ONE
Issue5We introduce a novel hybrid of two fields-Computational Fluid Dynamics (CFD) and Agent-Based Modeling (ABM)-as a powerful new technique for urban evacuation planning. CFD is a predominant technique for modeling airborne transport of contaminants, while ABM is a powerful approach for modeling social dynamics in populations of adaptive individuals. The hybrid CFD-ABM method is capable of simulating how large, spatially-distributed populations might respond to a physically realistic contaminant plume. We demonstrate the overall feasibility of CFD-ABM evacuation design, using the case of a hypothetical aerosol release in Los Angeles to explore potential effectiveness of various policy regimes. We conclude by arguing that this new approach can be powerfully applied to arbitrary population centers, offering an unprecedented preparedness and catastrophic event response tool.
Modeling the spread of methicillin-resistant staphylococcus aureus (MRSA) outbreaks throughout the hospitals in Orange County, CaliforniaLee, B. Y., McGlone, S. M., Wong, K. F., Yilmaz, S. L., Avery, T. R., Song, Y., Christie, R., Eubank, S., Brown, S. T., Epstein, J. M., Parker, J. I., Burke, D. S., Platt, R., & Huang, S. S.
Journal titleInfection Control and Hospital Epidemiology
Page(s)562-572Background. Since hospitals in a region often share patients, an outbreak of methicillin-resistant Staphylococcus aureus (MRSA) infection in one hospital could affect other hospitals. methods. Using extensive data collected from Orange County (OC), California, we developed a detailed agent-based model to represent patient movement among all OC hospitals. Experiments simulated MRSA outbreaks in various wards, institutions, and regions. Sensitivity analysis varied lengths of stay, intraward transmission coefficients (β), MRSA loss rate, probability of patient transfer or readmission, and time to readmission. results. Each simulated outbreak eventually affected all of the hospitals in the network, with effects depending on the outbreak size and location. Increasing MRSA prevalence at a single hospital (from 5% to 15%) resulted in a 2.9% average increase in relative prevalence at all other hospitals (ranging from no effect to 46.4%). Single-hospital intensive care unit outbreaks (modeled increase from 5% to 15%) caused a 1.4% average relative increase in all other OC hospitals (ranging from no effect to 12.7%). conclusion. MRSA outbreaks may rarely be confined to a single hospital but instead may affect all of the hospitals in a region. This suggests that prevention and control strategies and policies should account for the interconnectedness of health care facilities.
Economic cost and health care workforce effects of school closures in the U.SLempel, H., Epstein, J. M., & Hammond, R. A.
Journal titlePLoS CurrentsSchool closure is an important component of U.S. pandemic flu mitigation strategy, but has important costs. We give estimates of both the direct economic and health care impacts for school closure durations of 2, 4, 6, and 12 weeks under a range of assumptions. We find that closing all schools in the U.S. for four weeks could cost between $10 and $47 billion dollars (0.1-0.3% of GDP) and lead to a reduction of 6% to 19% in key health care personnel.
Coupled contagion dynamics of fear and disease: Mathematical and computational explorationsEpstein, J. M., Parker, J., Cummings, D., & Hammond, R. A.
Journal titlePLoS ONE
Issue12Background: In classical mathematical epidemiology, individuals do not adapt their contact behavior during epidemics. They do not endogenously engage, for example, in social distancing based on fear. Yet, adaptive behavior is well-documented in true epidemics. We explore the effect of including such behavior in models of epidemic dynamics. Methodology/Principal Findings: Using both nonlinear dynamical systems and agent-based computation, we model two interacting contagion processes: one of disease and one of fear of the disease. Individuals can "contract" fear through contact with individuals who are infected with the disease (the sick), infected with fear only (the scared), and infected with both fear and disease (the sick and scared). Scared individuals-whether sick or not-may remove themselves from circulation with some probability, which affects the contact dynamic, and thus the disease epidemic proper. If we allow individuals to recover from fear and return to circulation, the coupled dynamics become quite rich, and can include multiple waves of infection. We also study flight as a behavioral response. Conclusions/Significance: In a spatially extended setting, even relatively small levels of fear-inspired flight can have a dramatic impact on spatio-temporal epidemic dynamics. Self-isolation and spatial flight are only two of many possible actions that fear-infected individuals may take. Our main point is that behavioral adaptation of some sort must be considered.
Why model?Epstein, J. M.
Issue4This lecture treats some enduring misconceptions about modeling. One of these is that the goal is always prediction. The lecture distinguishes between explanation and prediction as modeling goals, and offers sixteen reasons other than prediction to build a model. It also challenges the common assumption that scientific theories arise from and 'summarize' data, when often, theories precede and guide data collection; without theory, in other words, it is not clear what data to collect. Among other things, it also argues that the modeling enterprise enforces habits of mind essential to freedom. It is based on the author's 2008 Bastille Day keynote address to the Second World Congress on Social Simulation, George Mason University, and earlier addresses at the Institute of Medicine, the University of Michigan, and the Santa Fe Institute.
Containing a large bioterrorist smallpox attack: a computer simulation approachLongini, I. M., Elizabeth Halloran, M., Nizam, A., Yang, Y., Xu, S., Burke, D. S., Cummings, D. A., & Epstein, J. M.
Journal titleInternational Journal of Infectious Diseases
Page(s)98-108Background: A bioterrorist release of smallpox is a constant threat to the population of the USA and other countries. Design: A stochastic simulation model of the spread of smallpox due to a large bioterrorist attack in a structured population was constructed. Disease natural history parameter estimates, time lines of behavioral activities, and control scenarios were based on the literature and on the consensus opinion of a panel of smallpox experts. Results: The authors found that surveillance and containment, i.e., isolation of known cases and vaccination of their close contacts, would be sufficient to effectively contain a large intentional smallpox release. Given that surveillance and containment measures are in place, preemptive vaccination of hospital workers would further reduce the number of smallpox cases and deaths but would require large numbers of prevaccinations. High levels of reactive mass vaccination after the outbreak begins would further reduce smallpox cases and deaths to a minimum, but would require even larger numbers of vaccinations. Reactive closure of schools would have a minimal effect. Conclusion: A rapid and well-organized response to a bioterrorist attack would be necessary for effective surveillance and containment to control spread. Preemptive vaccination of hospital workers and reactive vaccination of the target population would further limit spread, but at a cost of many more vaccinated. This cost in resources and potential harm due to vaccination will have to be weighed against the potential benefits should an attack occur. Prevaccination of the general population is not necessary.