Many resources for forensic scholars and practitioners, such as journal articles, guidance documents, and textbooks, address how to make a value of evidence assessment in the form of a likelihood ratio (LR) when deciding between two competing propositions. These texts often describe experts presenting their LR values to other parties in the judicial system, such as lawyers, judges, and potentially jurors, but few texts explicitly address how a recipient is expected to utilize the provided LR value. Those that do often imply, or directly suggest, a hybrid modification of Bayes' rule in which a decision maker multiplies their prior odds with another person's assessment of LR to obtain their posterior odds. In this paper, we illustrate how someone adhering to Bayesian reasoning would update their personal uncertainty in response to someone else presenting a personal LR value (or any other form of an opinion) and emphasize that the hybrid approach is a departure from Bayesian reasoning. We further consider implications of recipients adhering to Bayesian reasoning on the role and ideal content of expert's reports and testimony and address published responses to our 2017 paper (Lund and Iyer, 2017), where we previously argued that the hybrid equation is not supported by Bayesian reasoning.
翻译:用于法医学者和从业人员的许多资源,例如期刊文章、指导文件和教科书,都涉及如何在决定两个相互竞争的主张时以可能性比率(LR)的形式对证据进行评估的价值进行评估,这些案文往往描述专家向司法系统其他当事方,如律师、法官和可能的陪审员介绍他们的LR价值,但很少有案文明确述及如何期望接受者利用所提供的LR价值。那些常常暗示或直接暗示对Bayes规则的混合修改,其中,决策人将其先前与另一人评估LR评估的矛盾程度倍增,以获得其事后的胜算。在本文中,我们说明有人坚持Bayesian推理,在回应其他人提出个人LLV价值(或任何其他意见形式)时,将更新个人不确定性,并强调混合法背离了Bayesian推理。我们进一步审议了接受者坚持Bayesian推理对2017年专家报告和证词的作用和理想内容以及对我们发表的论文(Lund和Iyer,201717年)的答复的影响,我们以前曾认为,Bayes推理不支持Bayas等式的推理。