Freeman Michael D, Kohles Sean S
Department of Public Health and Preventive Medicine, Oregon Health and Science University School of Medicine, USA.
J Forensic Leg Med. 2010 Feb;17(2):67-77. doi: 10.1016/j.jflm.2009.09.006. Epub 2009 Oct 9.
Forensic Biomechanics is an analytic method intended for presentation in a court of law. The method consists of the reconstruction of an injury mechanism followed by a comparison between the injury risk of the mechanism and the injury tolerance of the individual. In recent years some courts have excluded such testimony based, in part, on the inability of experts to quantify the potential error of the methods they relied upon in reaching their conclusions. The application of Bayes' Law to a forensic test of truth in a disputed matter allows for quantification of the error inherent in the method through the conditioning of the pre-test probability of the test outcome with the true and false positive rate of the test. The result of the calculation is the Error Odds (O(E)) for the test, or the ratio of correct to incorrect tests. We present an Error Odds analysis of seven previously published case studies in Forensic Biomechanics as an illustration of the utility of the O(E) as a metric for admissibility of testimony in the courts, with a minimum Error Odds ratio of 10 proposed as a threshold. The results of our analysis yielded only 1 of 7 cases of applied Forensic Biomechanics that surpassed the threshold for admissible testimony of 10, with most the cases falling below an O(E) of 3. The results of the present study suggest that the forensic application of biomechanics is potentially fraught with error. We suggest that an Error Odds analysis be incorporated in Forensic Biomechanics as part of the analysis as a form of quality control and as demonstrable evidence of the accuracy of the methodology.
法医生物力学是一种旨在用于法庭陈述的分析方法。该方法包括对损伤机制的重建，随后将该机制的损伤风险与个体的损伤耐受性进行比较。近年来，一些法庭部分基于专家无法量化他们在得出结论时所依赖方法的潜在误差而排除了此类证词。将贝叶斯定律应用于有争议事项的法医真实性检验，可以通过用检验的真阳性率和假阳性率对检验结果的预检验概率进行条件设定来量化该方法中固有的误差。计算结果是该检验的误差几率（O(E)），即正确检验与错误检验的比率。我们对法医生物力学中七个先前发表的案例研究进行了误差几率分析，以说明O(E)作为法庭证词可采性度量的效用，并提议将最小误差几率比10作为阈值。我们的分析结果显示，在应用法医生物力学的7个案例中，只有1个超过了可采证词的阈值10，大多数案例的O(E)低于3。本研究结果表明，生物力学的法医应用可能充满误差。我们建议在法医生物力学分析中纳入误差几率分析，作为质量控制的一种形式以及该方法准确性的可证明证据。
