Validating TrueAllele® DNA mixture interpretation

Abstract: DNA mixtures with two or more contributors are a prevalent form of biological evidence. Mixture interpretation is complicated by the possibility of different genotype combinations that can explain the short tandem repeat (STR) data. Current human review simplifies this interpretation by applying thresholds to qualitatively treat STR data peaks as all‐or‐none events and assigning allele pairs equal likelihood. Computer review, however, can work instead with all the quantitative data to preserve more identification information. The present study examined the extent to which quantitative computer interpretation could elicit more identification information than human review from the same adjudicated two‐person mixture data. The base 10 logarithm of a DNA match statistic is a standard information measure that permits such a comparison. On eight mixtures having two unknown contributors, we found that quantitative computer interpretation gave an average information increase of 6.24 log units (min = 2.32, max = 10.49) over qualitative human review. On eight other mixtures with a known victim reference and one unknown contributor, quantitative interpretation averaged a 4.67 log factor increase (min = 1.00, max = 11.31) over qualitative review. This study provides a general treatment of DNA interpretation methods (including mixtures) that encompasses both quantitative and qualitative review. Validation methods are introduced that can assess the efficacy and reproducibility of any DNA interpretation method. An in‐depth case example highlights 10 reasons (at 10 different loci) why quantitative probability modeling preserves more identification information than qualitative threshold methods. The results validate TrueAllele^® DNA mixture interpretation and establish a significant information improvement over human review.     

Confidence interval of the likelihood ratio associated with mixed stain DNA evidence

Likelihood ratios are necessary to properly interpret mixed stain DNA evidence. They can flexibly consider alternate hypotheses and can account for population substructure. The likelihood ratio should be seen as an estimate and not a fixed value, because the calculations are functions of allelic frequency estimates that were estimated from a small portion of the population. Current methods do not account for uncertainty in the likelihood ratio estimates and are therefore an incomplete picture of the strength of the evidence. We propose the use of a confidence interval to report the consequent variation of likelihood ratios. The confidence interval is calculated using the standard forensic likelihood ratio formulae and a variance estimate derived using the Taylor expansion. The formula is explained, and a computer program has been made available. Numeric work shows that the evidential strength of DNA profiles decreases as the variation among populations increases.     

A Two‐Level Model for Evidence Evaluation in the Presence of Zeros*

Abstract: Likelihood ratios (LRs) provide a natural way of computing the value of evidence under competing propositions. We propose LR models for classification and comparison that extend the ideas of Aitken, Zadora, and Lucy and Aitken and Lucy to include consideration of zeros. Instead of substituting zeros by a small value, we view the presence of zeros as informative and model it using Bernoulli distributions. The proposed models are used for evaluation of forensic glass (comparison and classification problem) and paint data (comparison problem). Two hundred and sixty‐four glass samples were analyzed by scanning electron microscopy, coupled with an energy dispersive X‐ray spectrometer method and 36 acrylic topcoat paint samples by pyrolysis gas chromatography hyphened with mass spectrometer method. The proposed LR model gave very satisfactory results for the glass comparison problem and for most of the classification tasks for glass. Results of comparison of paints were also highly satisfactory, with only 3.0% false positive answers and 2.8% false negative answers.     

船员外派人身伤亡案件中船员服务机构地位辨析

船员外派是指船员被选派到境外,且通常在外籍船舶上提供劳动服务。《中华人民共和国船员条例》把船员服务机构定义为从事代理船员办理申请培训、考试、申领证书等有关手续,代理船员用人单位管理船员事务,提供船舶配员等船员服务业务的机构。结合《中华人民共和国船员条例》《中华人民共和国船员服务管理规定》以及2008年颁布的《中华人民共和国劳动合同法》,对在船员外派中船员服务机构的身份和法律地位进行分析,厘清船员、船员服务机构和境外船东三者关系,从而确定船员服务机构在此类案件中应承担的责任。     

Understanding of forensic expert reports by judges,defense lawyers and forensic professionals

Forensic scientists strongly advocate the use of likelihood ratios for expressing the diagnostic value of evidence in technical forensic reports. They call this the logically correct approach. The correct comprehension of such likelihood ratios by jurists, however, appears to be particularly problematic. The present research has empirically investigated this issue for defense lawyers and criminal judges. For comparative purposes forensic professionals, many of whom use the logically correct approach, were included in the study as well.

Using fictitious forensic reports, it was shown that proper understanding of likelihood ratios by jurists is quite poor, due mainly, but not exclusively, to the prosecutor's fallacy. Forensic professionals outperformed jurists to a large extent but made many mistakes themselves. It is further shown that participants’ self-expressed supposed level of understanding of logically correct conclusions is quite high and thus not justified by their levels of proper understanding. Suggestions for how to improve the situation are presented.     

论声纹鉴定意见的表述形式

本文针对目前国内外讨论比较热烈的声纹鉴定意见表述问题进行了评述.首先介绍了实践中正在使用的听觉分析法、声谱比对分析法、声学分析法、听觉-声学分析法和说话人自动识别五种鉴定方法,指出了各种方法的优缺点;然后对现存的二元判决、可能性等级、似然比和英国立场声明四种鉴定意见表述形式进行了介绍和评析,通过分析发现,上述四种意见表述形式都存在一定的问题,实践中选择何种形式表述鉴定意见要综合考虑其科学性、逻辑性、现实性和可行性等多种价值选项;最后认为解决该问题的根本方法是各相关领域的专家应加强在鉴定方法上的合作性的基础研究.     

Information‐Theoretical Assessment of the Performance of Likelihood Ratio Computation Methods

Performance of likelihood ratio (LR) methods for evidence evaluation has been represented in the past using, for example, Tippett plots. We propose empirical cross‐entropy (ECE) plots as a metric of accuracy based on the statistical theory of proper scoring rules, interpretable as information given by the evidence according to information theory, which quantify calibration of LR values. We present results with a case example using a glass database from real casework, comparing performance with both Tippett and ECE plots. We conclude that ECE plots allow clearer comparisons of LR methods than previous metrics, allowing a theoretical criterion to determine whether a given method should be used for evidence evaluation or not, which is an improvement over Tippett plots. A set of recommendations for the use of the proposed methodology by practitioners is also given.     

合同转让制度中权利义务责任的平衡观

合同转让包括合同权利的转让与合同义务的转让。合同债权转让不应以通知债务人为生效条件,以出让人与受让人达成转让合意为条件才符合合同法的基本原理,通知债务人是出让人转让债权的附随义务。在债权双重让与时,由于债权请求权属性与物权的不同,无法通过公示制度保护第三人利益,唯有强化受让人的注意义务才有助于实现当事人之间权益的平衡。合同义务的转让主要包括免责的债务承担与并存的债务承担,并存的债务承担在实务中的界定是较难把握的,免责的债务承担第三人承受移转债务负有给付义务。     

著作权利用制度的比较研究

著作权的利用是著作权法的一项重要制度 ,它使得著作权人、传播者、使用者的利益有机地结合起来 ,真正实现著作权法的目的和观念。比较研究各国著作权利用制度中的著作权转让、著作权的许可使用、著作权的质押 ,对完善我国著作权立法和司法实践有着重要的意义。     

谈谈医疗纠纷案件的举证责任——王连玉等诉太原市某医院医疗纠纷案

医疗行业属高风险行业，近年来随着人们维权意识的不断增强，医事纠纷呈逐年上升趋势，已经演化成为社会的热点问题之一。由于医患双方在医学知识掌握上的不平衡，造成了医疗纠纷处理过程中患方举证困难。2002年4月1日起实施的最高人民法院《民事证据规定》第4条第8项明确规定“因医疗行为引起的侵权诉讼，适用举证责任倒置”，即采取过错推定原则，成为医疗赔偿纠纷案件举证责任的一大进步。本文以一起医疗纠纷侵权诉讼为例，深刻剖析了医疗纠纷处理过程中的民事证明责任适用问题。