title: Testing likelihood ratios produced from complex DNA profiles.
abstract: The performance of any model used to analyse DNA profile evidence should be tested using simulation, large scale validation studies based on ground-truth cases, or alignment with trends predicted by theory. We investigate a number of diagnostics to assess the performance of the model using Hd true tests. Of particular focus in this work is the proportion of comparisons to non-contributors that yield a likelihood ratio (LR) higher than or equal to the likelihood ratio of a known contributor (LRPOI), designated as p, and the average LR for Hd true tests. Theory predicts that p should always be less than or equal to 1/LRPOI and hence the observation of this in any particular case is of limited use. A better diagnostic is the average LR for Hd true which should be near to 1. We test the performance of a continuous interpretation model on nine DNA profiles of varying quality and complexity and verify the theoretical expectations.
authors.affiliation: Forensic Science South Australia, 21 Divett Place, Adelaide, SA 5000, Australia; School of Biological Sciences, Flinders University, GPO Box 2100, Adelaide, SA 5001, Australia. Electronic address: Duncan.Taylor@sa.gov.au.
authors.forename: Duncan
authors.initials: D
authors.lastname: Taylor
authors.affiliation: ESR, Private Bag 92021, Auckland 1142, New Zealand.
authors.forename: John
authors.initials: J
authors.lastname: Buckleton
authors.affiliation: Principal Forensic Services Ltd., London, UK.
authors.forename: Ian
authors.initials: I
authors.lastname: Evett
mesh_terms: D004247:DNA / Q000235:genetics*; D006801:Humans; D016013:Likelihood Functions
chemical_list: D004247:DNA
keywords: DNA profile interpretation; Likelihood ratios; Mixtures; Performance tests