Variance in System Dynamics and Agent Based Modelling Using the SIR Model of Infectious Disease

Classical deterministic simulations of epidemiological processes, such as those based on System Dynamics, produce a single result based on a fixed set of input parameters with no variance between simulations. Input parameters are subsequently modified on these simulations using Monte-Carlo methods, to understand how changes in the input parameters affect the spread of results for the simulation. Agent Based simulations are able to produce different output results on each run based on knowledge of the local interactions of the underlying agents and without making any changes to the input parameters. In this paper we compare the influence and effect of variation within these two distinct simulation paradigms and show that the Agent Based simulation of the epidemiological SIR (Susceptible, Infectious, and Recovered) model is more effective at capturing the natural variation within SIR compared to an equivalent model using System Dynamics with Monte-Carlo simulation. To demonstrate this effect, the SIR model is implemented using both System Dynamics (with Monte-Carlo simulation) and Agent Based Modelling based on previously published empirical data.Comment: Proceedings of the 26th European Conference on Modelling and Simulation (ECMS), Koblenz, Germany, May 2012, pp 9-15, 201

Awareness and AIDS: A Political Economy Model

We present a simple political economy model that explains two major puzzles of government policies to combat HIV/AIDS epidemic: the lack of policy response in many countries where the epidemic is massive and the reversal of the downward trend in HIV prevalence in the countries that have adopted early agressive prevention campaigns. The model builds on the assumption that the unaware citizens impose a negative externality on the aware by increasing the risk of contagion. Prevention campaigns raise awareness of the current generation, which then partially transmit this awareness to the next generation, thus creating political support for the next-period awareness campaigns. The economy has two steady-state equilibria: the "good" one (with high awareness and low prevalence) and the "bad" one (low awareness, high prevalence). The "good" equilibrium is fragile, i.e. a sufficiently large exogenous drop in HIV prevalence undermines the next-generation political support for campaigns and makes the economy drift away towards the "bad" equilibrium.HIV/AIDS, voting, overlapping generations, awareness

Human behaviors: a threat for mosquito control?

Community involvement and the preventive behavior of households are considered to be at the heart of vector-control strategies. In this work, we consider a simple theoretical model that enables us to take into account human behaviors that may interfere with vector control. The model reflects the trade-off between perceived costs and observed efficacy. Our theoretical results emphasize that households may reduce their protective behavior in response to mechanical elimination techniques piloted by a public agent, leading to an increase of the total number of mosquitoes in the surrounding environment and generating a barrier for vector-borne diseases control. Our study is sufficiently generic to be applied to different arboviral diseases. It also shows that vector-control models and strategies have to take into account human behaviors.Comment: 27 pages, 7 figure

MULTI AGENT-BASED ENVIRONMENTAL LANDSCAPE (MABEL) - AN ARTIFICIAL INTELLIGENCE SIMULATION MODEL: SOME EARLY ASSESSMENTS

The Multi Agent-Based Environmental Landscape model (MABEL) introduces a Distributed Artificial Intelligence (DAI) systemic methodology, to simulate land use and transformation changes over time and space. Computational agents represent abstract relations among geographic, environmental, human and socio-economic variables, with respect to land transformation pattern changes. A multi-agent environment is developed providing task-nonspecific problem-solving abilities, flexibility on achieving goals and representing existing relations observed in real-world scenarios, and goal-based efficiency. Intelligent MABEL agents acquire spatial expressions and perform specific tasks demonstrating autonomy, environmental interactions, communication and cooperation, reactivity and proactivity, reasoning and learning capabilities. Their decisions maximize both task-specific marginal utility for their actions and joint, weighted marginal utility for their time-stepping. Agent behavior is achieved by personalizing a dynamic utility-based knowledge base through sequential GIS filtering, probability-distributed weighting, joint probability Bayesian correlational weighting, and goal-based distributional properties, applied to socio-economic and behavioral criteria. First-order logics, heuristics and appropriation of time-step sequences employed, provide a simulation-able environment, capable of re-generating space-time evolution of the agents.Environmental Economics and Policy,

The role of consumption and the financing of health investment under epidemic shocks

We study the behavior of consumption and health investment resulting from shocks undermining health capital accumulation. We examine the effects on subsequent life cycle of long-lived shocks undermining health with either an acceleration of health capital deterioration, or a decrease in health investment efficiency. We also address the issue of the financing of health investment. We provide new evidence based on nonparametric estimations which show complex non-linear interplay between life expectancy and health expenditure. We then develop a benchmark model where consumption and health capital enter additively in the utility function, featuring independence between the returns from ordinary consumption and health. Then, we depart from this setup by assuming non-additive preferences meaning that ordinary consumption also is crucial for health. We show that a shock undermining health which increases health expenditures and weakens the income base, not only affects savings but also compromises the consumption capacity, the human and physical capital of the economy, and undercuts the process of economic development. We also show that the magnitude of the effects strongly depends on the assumed preferences.consumption, health investments, savings, non-parametric estimation

Analysis and Validation of Models for Trust Dynamics

Treur, J. [Promotor]Hoogendoorn, M. [Copromotor