DNA commission of the International society for forensic genetics: Assessing the value of forensic biological evidence - Guidelines highlighting the importance of propositions. Part II: Evaluation of biological traces considering activity level propositions
DNA commission of the International society for forensic genetics: Assessing the value of forensic biological evidence - Guidelines highlighting the importance of propositions. Part II: Evaluation of biological traces considering activity level propositions
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DOI：
10.1016/j.fsigen.2019.102186
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发表时间：
2020-01-01
影响因子：
3.1
通讯作者：
Taylor, Duncan
中科院分区：
文献类型：
--
作者：
Gill, Peter;Hicks, Tacha;Taylor, Duncan
证据的价值很大程度上取决于命题。在两篇旨在就评估和命题表达的困难方面向社会提供建议的论文的第二篇中，我们主要集中在活动级别的命题上。这有助于法院解决“一个人的细胞材料是如何到达那里的？”这个问题。为了做到这一点，我们扩展了第一篇配套论文中概述的框架。首先，重要的是不要把结果和主张混为一谈。给出活动级命题的陈述旨在帮助解决间接转移与直接转移的问题，以及活动的时间，但重要的是要避免在命题中使用‘转移’一词。这是因为命题是由法院评估的，但DNA转移是科学家在解释其结果时需要考虑的一个因素。在知道结果和解决如下问题之前，理想的活动水平命题是设定的：X刺伤Y和不明身份的人刺伤Y，但X前一天遇到了Y。如果每个备选命题都为真，则科学家分配证据的概率，以推导出似然比。为了做到这一点，科学家问：a)“如果每个命题都是真的，人们的期望是什么？”B)“有哪些数据可以帮助评估这些提议的结果？”当提出证据时，科学家在命题框架的层次结构内工作。为DNA图谱计算的证据价值不能延续到层次结构中的更高级别-给定子来源、来源和活动水平命题的计算都是独立的。文中提供了一些例子来说明所信奉的原则以及此类评估应符合的标准。理想情况下，为了分配概率，分析师应该拥有/收集与相关案例相关的数据。这些数据必须与手头的案件有关，我们鼓励进一步研究和收集数据，以形成知识库。贝叶斯网络在帮助我们思考问题方面非常有用，因为它们迫使我们以一种逻辑的方式考虑所有相关的可能性。文中给出了一个算例。
The value of the evidence depends critically on propositions. In the second of two papers intended to provide advice to the community on difficult aspects of evaluation and the formulation of propositions, we focus primarily on activity level propositions. This helps the court address the question of "How did an individual's cell material get there?". In order to do this, we expand the framework outlined in the first companion paper. First, it is important not to conflate results and propositions. Statements given activity level propositions aim to help address issues of indirect vs direct transfer, and the time of the activity, but it is important to avoid use of the word 'transfer' in propositions. This is because propositions are assessed by the Court, but DNA transfer is a factor that scientists need to take into account for the interpretation of their results. Suitable activity level propositions are ideally set before knowledge of the results and address issues like: X stabbed Y vs. an unknown person stabbed Y but X met Y the day before. The scientist assigns the probability of the evidence, if each of the alternate propositions is true, to derive a likelihood ratio. To do this, the scientist asks: a) "what are the expectations if each of the propositions is true?" b) "What data are available to assist in the evaluation of the results given the propositions?" When presenting evidence, scientists work within the hierarchy of propositions framework. The value of evidence calculated for a DNA profile cannot be carried over to higher levels in the hierarchy - the calculations given sub-source, source and activity level propositions are all separate. A number of examples are provided to illustrate the principles espoused, and the criteria that such assessments should meet. Ideally in order to assign probabilities, the analyst should have/collect data that are relevant to the case in question. These data must be relevant to the case at hand and we encourage further research and collection of data to form knowledge bases. Bayesian Networks are extremely useful to help us think about a problem, because they force us to consider all relevant possibilities in a logical way. An example is provided.