Critical analysis of forensic cut-offs and legal thresholds: A coherent approach to inference and decision.
Details
State: Public
Version: author
Serval ID
serval:BIB_471A7BA55D75
Type
Article: article from journal or magazin.
Collection
Publications
Institution
Title
Critical analysis of forensic cut-offs and legal thresholds: A coherent approach to inference and decision.
Journal
Forensic science international
ISSN
1872-6283 (Electronic)
ISSN-L
0379-0738
Publication state
Published
Issued date
07/2018
Peer-reviewed
Oui
Volume
288
Pages
72-80
Language
english
Notes
Publication types: Journal Article
Publication Status: ppublish
Publication Status: ppublish
Abstract
In this paper we critically discuss the definition and use of cut-off values by forensic scientists, for example in forensic toxicology, and point out when and why such values - and ensuing categorical conclusions - are inappropriate concepts for helping recipients of expert information with their questions of interest. Broadly speaking, a cut-off is a particular value of results of analyses of a target substance (e.g., a toxic substance or one of its metabolites in biological sample from a person of interest), defined in a way such as to enable scientists to suggest conclusions regarding the condition of the person of interest. The extent to which cut-offs can be reliably defined and used is not unanimously agreed within the forensic science community, though many practitioners - especially in operational laboratories - rely on cut-offs for reasons such as ease of use and simplicity. In our analysis, we challenge this practice by arguing that choices made for convenience should not be to the detriment of balance and coherence. To illustrate our discussion, we will choose the example of alcohol markers in hair, used widely by forensic toxicologists to reach conclusions regarding the drinking behaviour of individuals. Using real data from one of the co-authors' own work and recommendations of cut-offs published by relevant professional organisations, we will point out in what sense cut-offs are incompatible with current evaluative guidelines (e.g., [31]) and show how to proceed logically without cut-offs by using a standard measure for evidential value. Our conclusions run counter to much current practice, but are inevitable given the inherent definitional and conceptual shortcomings of scientific cut-offs. We will also point out the difference between scientific cut-offs and legal thresholds and argue that the latter - but not the former - are justifiable and can be dealt with in logical evaluative procedures.
Keywords
Biomarkers/analysis, Decision Making, Forensic Toxicology/legislation & jurisprudence, Forensic Toxicology/methods, Glucuronates/analysis, Hair/chemistry, Humans, Narcotics/blood, Reference Values, Substance Abuse Detection/legislation & jurisprudence, Substance Abuse Detection/methods, Substance-Related Disorders/diagnosis, Cut-offs, Forensic science, Interpretation, Legal threshold, Toxicological analyses
Pubmed
Web of science
Open Access
Yes
Create date
12/05/2018 10:07
Last modification date
20/08/2019 14:53