title: Helping formulate propositions in forensic DNA analysis.
abstract: The Bayesian paradigm is the preferred approach to evidence interpretation. It requires the evaluation of the probability of the evidence under at least two propositions. The value of the findings (i.e., our LR) will depend on these propositions and the case information, so it is crucial to identify which propositions are useful for the case at hand. Previously, a number of principles have been advanced and largely accepted for the evaluation of evidence. In the evaluation of traces involving DNA mixtures there may be more than two propositions possible. We apply these principles to some exemplar situations. We also show that in some cases, when there are no clear propositions or no defendant, a forensic scientist may be able to generate explanations to account for observations. In that case, the scientist plays a role of investigator, rather than evaluator. We believe that it is helpful for the scientist to distinguish those two roles.
authors.affiliation: ESR Ltd., Private Bag 92021 Auckland, New Zealand. Electronic address: john.buckleton@esr.cri.nz.
authors.forename: John
authors.initials: J
authors.lastname: Buckleton
authors.affiliation: ESR Ltd., Private Bag 92021 Auckland, New Zealand; Department of Statistics, University of Auckland, Private Bag 92019, Auckland, New Zealand.
authors.forename: Jo-Anne
authors.initials: JA
authors.lastname: Bright
authors.affiliation: Forensic Science South Australia, 21 Divett Place, SA 5000, Australia.
authors.forename: Duncan
authors.initials: D
authors.lastname: Taylor
authors.affiliation: Principal Forensic Services Ltd., London, UK.
authors.forename: Ian
authors.initials: I
authors.lastname: Evett
authors.affiliation: University of Lausanne, Institut de police scientifique et Fondation pour la formation continue universitaire lausannoise, Lausanne-Dorigny, Switzerland.
authors.forename: Tacha
authors.initials: T
authors.lastname: Hicks
authors.affiliation: 'Advance Forensic Science', St. Andrews, Fife, UK; School of Contemporary Sciences, University of Abertay Dundee, Bell Street, Dundee DD1 1HG, UK.
authors.forename: Graham
authors.initials: G
authors.lastname: Jackson
authors.affiliation: Department of Statistics, University of Auckland, Private Bag 92019, Auckland, New Zealand.
authors.forename: James M
authors.initials: JM
authors.lastname: Curran
mesh_terms: D003210:Concept Formation; D016172:DNA Fingerprinting / Q000379:methods*; D006801:Humans; D024382:Professional Role
keywords: Evaluation; Forensic DNA interpretation; Investigation; Mixtures; Propositions; Role