title: The variability in likelihood ratios due to different mechanisms.
abstract: Recently there has been a drive towards standardisation of forensic DNA interpretation methods resulting in the uptake of probabilistic interpretation software. Some of these software solutions utilise Markov chain Monte Carlo techniques (MCMC). They will not produce an identical answer after repeat interpretations of the same evidence profile because of the Monte Carlo aspect. This is a new source of variability within the forensic DNA analysis process. In this paper we explore the size of the MCMC variability within the interpretation software STRmix™ compared to other sources of variability in forensic DNA profiling including PCR, capillary electrophoresis load and injection, and the makeup of allele frequency databases. The MCMC variability within STRmix™ was shown to be the smallest source of variability in this process.
authors.affiliation: ESR Ltd, Private Bag 92021, Auckland 1142, New Zealand; University of Auckland, Department of Statistics, Private Bag 92019, Auckland 1142, New Zealand. Electronic address: Jo.bright@esr.cri.nz.
authors.forename: Jo-Anne
authors.initials: JA
authors.lastname: Bright
authors.affiliation: ESR Ltd, Private Bag 92021, Auckland 1142, New Zealand.
authors.forename: Kate E
authors.initials: KE
authors.lastname: Stevenson
authors.affiliation: University of Auckland, Department of Statistics, Private Bag 92019, Auckland 1142, New Zealand.
authors.forename: James M
authors.initials: JM
authors.lastname: Curran
authors.affiliation: ESR Ltd, Private Bag 92021, Auckland 1142, New Zealand.
authors.forename: John S
authors.initials: JS
authors.lastname: Buckleton
mesh_terms: D004247:DNA / Q000235:genetics; D053803:Forensic Genetics; D006801:Humans; D016013:Likelihood Functions; D008390:Markov Chains; D009010:Monte Carlo Method
chemical_list: D004247:DNA
keywords: Forensic DNA; Interpretation; Likelihood ratio; MCMC; STRmix™