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Willy Aspinall (Bristol) - Expert elicitation of scientific uncertainties using Cooke's Classical Model: applicability to COVID-19 risk assessments

Wednesday 10th June 2020 - 14:05 to 14:35
INI Seminar Room 1

Abstract: Many COVID-19 research projects have elements of forecasting, planning and urgent decision-making that must be executed before solid data are available.  Some approaches, which neglect formal uncertainty quantification, can compromise estimates of low-probability/high-consequence outcomes: this could be a critical flaw when evaluating complex COVID-19 risks.  Adopting a structured elicitation procedure can reduce risk assessment weaknesses associated with inappropriate and sometimes misleading parameter and modelling assumptions. Several varieties of expert elicitation are practised, often categorised as 'behavioural aggregation' or 'mathematical aggregation'.  Cooke's Classical Model is of the latter class and we have used it extensively to provide scientific support for critical public safety decisions during volcanic eruptions. The method has garnered a track record for formalising the determination of input variable or parameter uncertainty distributions for risk modelling when conventional data do not exist or are undependable, e.g. with the adaptive Bayes Belief Net formalism for combining disparate strands of uncertain scientific evidence.  The underpinning algorithm provides empirical control on expert performance scoring and weighting for combining experts’ judgments into an auditable, rational consensus.  While it has become an established and validated elicitation procedure in many disciplines, this approach has not found widespread use in epidemiological modelling, even though it is well-suited to risk issues relating to emergent zoonoses.  We briefly summarise the principles of the method and how it is applied to real-world critical decision problems, mentioning a few case studies closely analogous to the present coronavirus problem.   Resources: The best link to materials relevant to my talk is Roger Cooke’s website: <> It has a lot of relevant stuff, and includes a link to a video of a 1-hour talk on the Classical Model for Structured Expert Judgment, which I gave at CDC Atlanta in May 2107.  


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Presentation Material: 
University of Cambridge Research Councils UK
    Clay Mathematics Institute London Mathematical Society NM Rothschild and Sons