title: Incorporating parameter uncertainty into Quantitative Microbial Risk Assessment (QMRA).
abstract: Modern statistical models and computational methods can now incorporate uncertainty of the parameters used in Quantitative Microbial Risk Assessments (QMRA). Many QMRAs use Monte Carlo methods, but work from fixed estimates for means, variances and other parameters. We illustrate the ease of estimating all parameters contemporaneously with the risk assessment, incorporating all the parameter uncertainty arising from the experiments from which these parameters are estimated. A Bayesian approach is adopted, using Markov Chain Monte Carlo Gibbs sampling (MCMC) via the freely available software, WinBUGS. The method and its ease of implementation are illustrated by a case study that involves incorporating three disparate datasets into an MCMC framework. The probabilities of infection when the uncertainty associated with parameter estimation is incorporated into a QMRA are shown to be considerably more variable over various dose ranges than the analogous probabilities obtained when constants from the literature are simply 'plugged' in as is done in most QMRAs. Neglecting these sources of uncertainty may lead to erroneous decisions for public health and risk management.
authors.affiliation: Queensland University of Technology, George Street, Brisbane, QLD 4000, Australia. Margaret.Donald@student.qut.edu.au
authors.forename: Margaret
authors.initials: M
authors.lastname: Donald
authors.forename: Kerrie
authors.initials: K
authors.lastname: Mengersen
authors.forename: Simon
authors.initials: S
authors.lastname: Toze
authors.forename: Jatinder P S
authors.initials: JP
authors.lastname: Sidhu
authors.forename: Angus
authors.initials: A
authors.lastname: Cook
mesh_terms: D001499:Bayes Theorem; D006801:Humans; D008390:Markov Chains; D008954:Models, Biological; D015233:Models, Statistical; D009010:Monte Carlo Method; D018570:Risk Assessment / Q000379:methods*; D012480:Salmonella Infections / Q000453:epidemiology*; D012486:Salmonella typhimurium / Q000502:physiology*; D013472:Sunlight; D035501:Uncertainty; D014871:Water Microbiology; D014904:Western Australia / Q000453:epidemiology