Taroni F., Bozza S., Biedermann A. 2020, Decision theory, in: Handbook of Forensic Statistics, Banks D. L., Kafadar K., Kaye D.H., Tackett M. (Eds.), Chapman & Hall/CRC Handbooks of Modern Statistical Methods, Chapter 5, 103–130.
Posted: 25 Feb 2021
Date Written: November 6, 2020
Forensic scientists, lawyers and other participants of the legal process are routinely faced with problems of making decisions under circumstances of uncertainty. Uncertainty relates to propositions of interest that are not completely known by the decision-maker at the time when a decision needs to be made. Propositions may relate to the source or nature of forensic traces, marks and objects. For example, with friction ridge marks, propositions of interest may be ‘Does this fingermark come from the person of interest (POI) or from some unknown person?’. In forensic document examination, a scientist may ask ‘Is this a genuine document or has it been modified (e.g., page substitution)?’. In forensic anthropology the question ‘Are these human remains?’ may arise, and so on. Replying in one way or another to such questions may be perceived as uncomfortable since knowledge about the relevant underlying truth-state of the world is incomplete to some extent. For example, in typical real-world applications of forensic science it is not known with certainty, when deciding to consider a POI as the source of a particular fingermark, whether the POI is in fact the source of the fingermark. Similarly, at an advanced stage of the legal process, the question of whether to convict or acquit a POI (i.e. the verdict) needs to be made in the presence of incomplete knowledge about whether or not the POI truly is the offender. There are analogies between the above questions, in terms of their logical underpinnings, that can be studied, analysed and described using formal methods, such as decision theory, which is the main aim of this chapter.
Keywords: Decision theory, forensic science, decision-making in the law, statistics
Suggested Citation: Suggested Citation