似然比在钢丝钳钳剪痕迹比对中的可行性探究

Research on the Feasibility of Likelihood Ratio in Comparison of Cutting Marks of Wire Pliers

将基于似然比的证据评估体系引入到钢丝钳钳剪痕迹比对中,为检验定量化的研究提供一种新方法、新思路。通过收集200份钢丝钳钳剪的铜丝断头,并对内刃直剪产生的断头峰角的角度、外刃直剪产生的断头峰角的角度等特征进行统计、建库、分析,而后分别求得内外刃形成的峰角角度在钳剪断头中的出现率,求出似然比值。似然比值与对应的似然比等级表中的证据支持强度符合实验结果,所选用的特征数量越多,似然比值越大,对认定同一或者否定同一的证据支持力度也就越强。似然比应用于钢丝钳钳剪痕迹比对中具有可行性。

This paper introduces the evidence evaluation system based on likelihood ratio into the comparison of pliers cutting marks,which provides a new method and a new idea for the examination of quantitative research.By collecting 200 copper wire broken heads of pliers and cutters,the angle of the peak angle of the cutting head produced by the inner blade straight cut and the angle of the peak angle of the cutting head produced by the outer blade straight cut are analyzed.Then,the occurrence rate of the peak angle of the inner blade and the outer blade in the cutting head is calculated and the likelihood ratio is obtained.The likelihood ratio and the supporting strength of the evidence in the corresponding likelihood ratio scale are consistent with the experimental results.The more the number of features selected is,the greater the likelihood ratio is,and the stronger the supporting strength of the evidence to identify or deny the same is.It is feasible to apply the likelihood ratio to the comparison of cutting marks of wire pliers.