title: Utilising allelic dropout probabilities estimated by logistic regression in casework.
abstract: Some advanced methods for DNA profile interpretation require a probability for the event of dropout. Methods have been suggested based on logistic regression. Two of these respectively use a proxy for template that is constant across loci and one that is modelled using an exponential curve. Both of these methods allow different modelling constants from each locus. A variant of the model using an exponential curve is discussed. This variant constrains the constants to be the same for every locus. We test these two methods and the variant by developing the constants (training) on one set of data and testing them on another. This mimics the likely use in casework. We find that the new variant appears to be the most useful in that it performs better than the other two options when trained on one data set and used on another. The hypothesised reason for this is that locus to locus variation in amplification efficiency varies with time, multimix batch, or from sample to sample.
authors: ESR Ltd, Private Bag 92021, Auckland, New Zealand. Electronic address: john.buckleton@esr.cri.nz.
authors: John
authors: J
authors: Buckleton
authors: Department of Statistics, University of Auckland, Private Bag 92019, Auckland, New Zealand.
authors: Hannah
authors: H
authors: Kelly
authors: ESR Ltd, Private Bag 92021, Auckland, New Zealand; Department of Statistics, University of Auckland, Private Bag 92019, Auckland, New Zealand.
authors: Jo-Anne
authors: JA
authors: Bright
authors: Forensic Science South Australia, 21 Divett Place, SA 5000, Australia.
authors: Duncan
authors: D
authors: Taylor
authors: Department of Mathematical Sciences, Aalborg University, Fredrik Bajers Vej 7G, DK-9220 Aalborg East, Denmark; Section of Forensic Genetics, Department of Forensic Medicine, Faculty of Health Sciences, University of Copenhagen, Denmark.
authors: Torben
authors: T
authors: Tvedebrink
authors: Department of Statistics, University of Auckland, Private Bag 92019, Auckland, New Zealand.
authors: James M
authors: JM
authors: Curran
mesh_terms: D000483:Alleles; D001774:Blood Chemical Analysis; D004247:DNA / Q000302:isolation & purification; D016172:DNA Fingerprinting; D019075:Electrophoresis, Capillary; D006801:Humans; D016013:Likelihood Functions; D016015:Logistic Models; D008297:Male; D008957:Models, Genetic; D012661:Semen / Q000737:chemistry
chemical_list: D004247:DNA
keywords: Dropout; Forensic DNA interpretation; Logistic regression; Low template