Three studies investigated lay people’s perceptions of the relative strength of various conclusions that a forensic scientist might present about whether two items (fingerprints, biological samples) have a common source. Lay participants made a series of judgments about which of two conclusions seemed stronger for proving the items had a common source. The data were fitted to Thurstone–Mosteller paired comparison models to obtain rank-ordered lists of the various statements and an indication of the perceived differences among them. The results reveal the perceived strength of several types of statements, relative to one another, including verbal statements regarding strength of support (e.g. ‘extremely strong support for same source’), source probability statements (e.g. ‘highly probable same source’), random match probabilities (e.g. RMP = 1 in 100 000), likelihood ratios, and categorical statements (e.g. ‘identification’). These comparisons in turn provide insight into whether particular statements about the strength of forensic evidence convey the intended meaning and will be interpreted in a manner that is justifiable and appropriate. Disciplines Forensic Science and Technology Comments This is a manuscript of an article published as Thompson, William C., Rebecca Hofstein Grady, Eric Lai, and Hal S. Stern. "Perceived strength of forensic scientists’ reporting statements about source conclusions." Law, Probability and Risk 17, no. 2 (2018): 133-155. Posted with permission of CSAFE. This article is available at Iowa State University Digital Repository: https://lib.dr.iastate.edu/csafe_pubs/22 Perceived strength of forensic scientists’ reporting statements about source conclusions WILLIAM C. THOMPSONy, REBECCA HOFSTEIN GRADY, ERIC LAI AND HAL S. STERN University of California, Irvine, CA, USA Three studies investigated lay people’s perceptions of the relative strength of various conclusions that a forensic scientist might present about whether two items (fingerprints, biological samples) have a common source. Lay participants made a series of judgments about which of two conclusions seemed stronger for proving the items had a common source. The data were fitted to Thurstone– Mosteller paired comparison models to obtain rank-ordered lists of the various statements and an indication of the perceived differences among them. The results reveal the perceived strength of several types of statements, relative to one another, including verbal statements regarding strength of support (e.g. ‘extremely strong support for same source’), source probability statements (e.g. ‘highly probable same source’), random match probabilities (e.g. RMP1⁄4 1 in 100 000), likelihood ratios, and categorical statements (e.g. ‘identification’). These comparisons in turn provide insight into whether particular statements about the strength of forensic evidence convey the intended meaning and will be interpreted in a manner that is justifiable and appropriate.

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法医科学家关于来源结论的报告陈述的感知强度

三项研究调查了外行对法医科学家可能提出的关于两个项目（指纹、生物样本）是否具有共同来源的各种结论的相对强度的看法。非专业参与者对两个结论中哪一个更能证明这些项目具有共同来源做出了一系列判断。将数据拟合到 Thurstone-Mosteller 配对比较模型，以获得各种陈述的排序列表以及它们之间感知差异的指示。结果揭示了几种类型的陈述相对于彼此的感知强度，包括关于支持强度的口头陈述（例如“对同一来源的极强支持”）、来源概率陈述（例如“极有可能的同一来源”）、随机匹配概率（例如 RMP = 100 000 分之一）、似然比和分类陈述（例如“识别”）。反过来，这些比较有助于深入了解有关法医证据强度的特定陈述是否传达了预期含义，以及是否会以合理和适当的方式进行解释。学科法医科学与技术评论 这是一篇以 Thompson、William C.、Rebecca Hofstein Grady、Eric Lai 和 Hal S. Stern 发表的文章的手稿。“法医科学家关于来源结论的报告陈述的感知强度。” 法律、概率和风险 17，没有。2 (2018): 133-155。经 CSAFE 许可发布。本文可在爱荷华州立大学数字资源库中获取：https://lib.dr.iastate。edu/csafe_pubs/22 法医科学家关于来源结论的报告陈述的感知强度 WILLIAM C. THOMPSONy、REBECCA HOFSTEIN GRADY、ERIC LAI 和 HAL S. STERN 美国加利福尼亚州欧文加利福尼亚大学 三项研究调查了非专业人士对亲属的看法法医科学家可能提出的关于两个项目（指纹、生物样本）是否具有共同来源的各种结论的强度。非专业参与者对两个结论中哪一个更能证明这些项目具有共同来源做出了一系列判断。将数据拟合到 Thurstone-Mosteller 配对比较模型，以获得各种陈述的排序列表以及它们之间感知差异的指示。结果揭示了几种类型陈述的感知强度，相对于彼此，包括关于支持强度的口头陈述（例如“对同一来源的极强支持”）、来源概率陈述（例如“极有可能的同一来源”）、随机匹配概率（例如 RMP1⁄4 1 in 100 000）、似然比和分类陈述（例如“身份证明”）。反过来，这些比较有助于深入了解有关法医证据强度的特定陈述是否传达了预期含义，以及是否会以合理和适当的方式进行解释。