Publications by authors named "Gregory S Parnell"

In counterterrorism risk management decisions, the analyst can choose to represent terrorist decisions as defender uncertainties or as attacker decisions. We perform a comparative analysis of probabilistic risk analysis (PRA) methods including event trees, influence diagrams, Bayesian networks, decision trees, game theory, and combined methods on the same illustrative examples (container screening for radiological materials) to get insights into the significant differences in assumptions and results. A key tenent of PRA and decision analysis is the use of subjective probability to assess the likelihood of possible outcomes.

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The tragic events of 9/11 and the concerns about the potential for a terrorist or hostile state attack with weapons of mass destruction have led to an increased emphasis on risk analysis for homeland security. Uncertain hazards (natural and engineering) have been successfully analyzed using probabilistic risk analysis (PRA). Unlike uncertain hazards, terrorists and hostile states are intelligent adversaries who can observe our vulnerabilities and dynamically adapt their plans and actions to achieve their objectives.

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In 2006, the Department of Homeland Security (DHS) completed its first Bioterrorism Risk Assessment (BTRA), intended to be the foundation for DHS's subsequent biennial risk assessments mandated by Homeland Security Presidential Directive 10 (HSPD-10). At the request of DHS, the National Research Council established the Committee on Methodological Improvements to the Department of Homeland Security's Biological Agent Risk Analysis to provide an independent, scientific peer review of the BTRA. The Committee found a number of shortcomings in the BTRA, including a failure to consider terrorists as intelligent adversaries in their models, unnecessary complexity in threat and consequence modeling and simulations, and a lack of focus on risk management.

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