An Investigation into Compound Likelihood Ratios for Forensic DNA Mixtures

Wivell, Richard; Kelly, Hannah; Kokoszka, Jason; Daniels, Jace; Dickson, Laura; Buckleton, John; Bright, Jo-Anne

doi:10.3390/genes14030714

Open AccessArticle

An Investigation into Compound Likelihood Ratios for Forensic DNA Mixtures

by

Richard Wivell

^1,*,

Hannah Kelly

¹,

Jason Kokoszka

²,

Jace Daniels

²,

Laura Dickson

³,

John Buckleton

^1,4 and

Jo-Anne Bright

¹

Institute of Environmental Science and Research Limited, Private Bag 92012, Auckland, New Zealand

²

Alabama Department of Forensic Sciences, 1 Forensic Drive, Mobile, AL 36617, USA

³

Washoe County Sherriff’s Office, Forensic Science Division, 911 Parr Blvd, Reno, NV 89512, USA

⁴

Department of Statistics, University of Auckland, Private Bag 92019, Auckland, New Zealand

^*

Author to whom correspondence should be addressed.

Genes 2023, 14(3), 714; https://doi.org/10.3390/genes14030714

Submission received: 22 February 2023 / Revised: 8 March 2023 / Accepted: 10 March 2023 / Published: 14 March 2023

(This article belongs to the Special Issue Forensic DNA Mixture Interpretation and Probabilistic Genotyping)

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Abstract

Simple propositions are defined as those with one POI and the remaining contributors unknown under H_p and all unknown contributors under H_a. Conditional propositions are defined as those with one POI, one or more assumed contributors, and the remaining contributors (if any) unknown under H_p, and the assumed contributor(s) and N unknown contributors under H_a. In this study, compound propositions are those with multiple POI and the remaining contributors unknown under H_p and all unknown contributors under Ha. We study the performance of these three proposition sets on thirty-two samples (two laboratories × four NOCs × four mixtures) consisting of four mixtures, each with N = 2, N = 3, N = 4, and N = 5 contributors using the probabilistic genotyping software, STRmix™. In this study, it was found that conditional propositions have a much higher ability to differentiate true from false donors than simple propositions. Compound propositions can misstate the weight of evidence given the propositions strongly in either direction.

Keywords: forensic DNA analysis; mixtures; propositions; likelihood ratios

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MDPI and ACS Style

Wivell, R.; Kelly, H.; Kokoszka, J.; Daniels, J.; Dickson, L.; Buckleton, J.; Bright, J.-A. An Investigation into Compound Likelihood Ratios for Forensic DNA Mixtures. Genes 2023, 14, 714. https://doi.org/10.3390/genes14030714

AMA Style

Wivell R, Kelly H, Kokoszka J, Daniels J, Dickson L, Buckleton J, Bright J-A. An Investigation into Compound Likelihood Ratios for Forensic DNA Mixtures. Genes. 2023; 14(3):714. https://doi.org/10.3390/genes14030714

Chicago/Turabian Style

Wivell, Richard, Hannah Kelly, Jason Kokoszka, Jace Daniels, Laura Dickson, John Buckleton, and Jo-Anne Bright. 2023. "An Investigation into Compound Likelihood Ratios for Forensic DNA Mixtures" Genes 14, no. 3: 714. https://doi.org/10.3390/genes14030714

APA Style

Wivell, R., Kelly, H., Kokoszka, J., Daniels, J., Dickson, L., Buckleton, J., & Bright, J.-A. (2023). An Investigation into Compound Likelihood Ratios for Forensic DNA Mixtures. Genes, 14(3), 714. https://doi.org/10.3390/genes14030714

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

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An Investigation into Compound Likelihood Ratios for Forensic DNA Mixtures

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