A comment on the PCAST report: Skip the “match”/“non-match” stage

Morrison, Geoffrey Stewart; Kaye, David H.; Balding, David J.; Taylor, Duncan; Dawid, Philip; Aitken, Colin; Gittelson, Simone; Zadora, Grzegorz; Robertson, Bernard; Willis, Sheila; Pope, Sue; Neil, Martin; Martire, Kristy A.; Hepler, Amanda B.; Gill, Richard D.; Jamieson, Allan; Zoete, Jacob de; Ostrum, R. Brent; Caliebe, Amke

doi:10.1016/j.forsciint.2016.10.018

Cited by 22 publications

(13 citation statements)

References 8 publications

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“…The use of this type of techniques to infer the source of forensic traces has been explicitly discouraged by some (European Network of Forensic Science Institutes (ENFSI), 2016) but encouraged by others (National Research Council (NRC) of the National Academies, 2009; President's Council of Advisors on Science and Technology (PCAST), 2016). We agree with Champod (2015), Evett et al (2017) and Morrison et al (2017) in that error rates are only an average measure of performance over a population and do not provide information regarding the support of the evidence in individual cases.…”

Section: Discussionmentioning

confidence: 46%

Defence against the modern arts: the curse of statistics—Part II: ‘Score-based likelihood ratios’

Neumann

Ausdemore

2020

Law, Probability and Risk

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For several decades, legal and scientific scholars have argued that conclusions from forensic examinations should be supported by statistical data and reported within a probabilistic framework. Multiple models have been proposed to quantify the probative value of forensic evidence. Unfortunately, several of these models rely on adhoc strategies that are not scientifically sound. The opacity of the technical jargon used to present these models and their results, and the complexity of the techniques involved make it very difficult for the untrained user to separate the wheat from the chaff. This series of papers is intended to help forensic scientists and lawyers recognise limitations and issues in tools proposed to interpret the results of forensic examinations. This paper focuses on tools that have been proposed to leverage the use of similarity scores to assess the probative value of forensic findings. We call this family of tools "score-based likelihood ratios". In this paper, we present the fundamental concepts on which these tools are built, we describe some specific members of this family of tools, and we explore their convergence to the Bayes factor through an intuitive geometrical approach and through simulations. Finally, we discuss their validation and their potential usefulness as a decision-making tool in forensic science.

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Section: Discussionmentioning

confidence: 46%

Defence against the modern arts: the curse of statistics—Part II: ‘Score-based likelihood ratios’

Neumann

Ausdemore

2020

Law, Probability and Risk

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“…The logical approach has done much to clarify the rather woolly inference that historically has been associated with the match paradigm but it has also demonstrated the considerable advantages of the single stage approach implied by the assignment of weight through the calculation of the likelihood ratio, over the rather clumsy and inefficient two-stage approach implied by the match paradigm. This has already been pointed out by Morrison et al [4].…”

Section: The Match Paradigmsupporting

confidence: 59%

“…It is necessary for the scientist to consider the probability 4 of the observations given the truth of each of the two propositions in turn.…”

Section: C Probability Of the Observationsmentioning

confidence: 99%

“…This paper is written in response to a recent report on forensic science of the US President's Council of Advisors on Science and Technology (PCAST) [1]. There have already been a number of responses to the report from the forensic community [2][3][4][5][6][7] which have resulted in an addendum to the report [8]. Our main concern is that the report (and its addendum) fails to recognise the advances in the logic of forensic inference that have taken place over the last 50 years or so.…”

Section: Introductionmentioning

confidence: 99%

“…A source level DNA proposition would specify the nature of the recovered material, e.g. "the semen came from the POI" 4. This could be a probability density, depending on the nature of the observations.…”

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confidence: 99%

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Finding the way forward for forensic science in the US—A commentary on the PCAST report

Evett¹,

Berger

Buckleton

et al. 2017

Forensic Science International

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A recent report by the US President's Council of Advisors on Science and Technology (PCAST), (2016) has made a number of recommendations for the future development of forensic science. Whereas we all agree that there is much need for change, we find that the PCAST report recommendations are founded on serious misunderstandings. We explain the traditional forensic paradigms of match and identification and the more recent foundation of the logical approach to evidence evaluation. This forms the groundwork for exposing many sources of confusion in the PCAST report. We explain how the notion of treating the scientist as a black box and the assignment of evidential weight through error rates is overly restrictive and misconceived. Our own view sees inferential logic, the development of calibrated knowledge and understanding of scientists as the core of the advance of the profession.

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