似然比在赤足足迹检验鉴定中的应用

Trial Application of Likelihood Ratio Test into Barefoot Print Examination

目的探索似然比检验方法用于赤足足迹鉴定,并对检验结果作量化分析。方法收集300份赤足足迹样本,并对它们的拇趾形状、跖前(后)缘形状、足弓类型、足跟类型、足趾分布是否为重叠型以及第三趾中心点与第二、四趾中心点连线的关系等项特征进行统计,然后计算出各种特征在赤足足迹中的出现概率,计算似然比值。结果对应于6个似然比等级,关联的特征性足迹类型越多则累积似然比值越大,证据强度越高。结论似然比检验可用于赤足足迹的检验鉴定。

Objective Exploring to apply the likelihood ratio test into barefoot print examination through the quantitative analysis of the test results. Methods 300 samples of human barefoot prints were collected and statistically recorded of their seven features of toe shape, both leading and trailing edge shape of sole, arch type, heel shape, overlapped digits, and the relation between the central point of the third digit and the line connecting the central points of the second and fourth digits. The probability of each above feature that appears in the barefoot prints was calculated in order to obtain each relevant likelihood ratio and the product （cumulative likelihood ratio） by multiplication of each one. Results Corresponding to the six grades of likelihood ratio, the more involvement of the featured types of footprint, the bigger value of the cumulative likelihood ratio, and consequently the higher strength of evidence. Conclusion The likelihood ratio test can be applied into the examination of barefoot print.