Ross A H
University of Tennessee, Department of Anthropology, Knoxville, USA.
J Forensic Sci. 1996 Jul;41(4):629-33.
Caliber estimation from entrance defects has long been rejected by forensic scientists. This appears to be a consequence of soft tissue perspective of forensic pathologists. This study examined the relation between caliber and cranial entrance defects and maximum cranial thickness. The calibers considered in this inquiry were .22, .25, .32, and .38. The sample consisted of 73 specimens obtained at autopsy (thirty-seven of .22 caliber, five of .25, six of .32, and twenty-five of .38). To test the strength of the relation between caliber, minimum diameter, and maximum thickness Pearson correlation coefficients were conducted. The strongest relationship was observed between caliber and minimum diameter. A relationship between minimum diameter and maximum thickness was also observed. To test the null hypothesis that the mean minimum diameter is not significantly different between calibers an analysis of variance procedure was performed. The ANOVA yielded a strong relationship between dependent variable minimum diameter and caliber. Multiple regression analysis measuring the association between minimum diameter, caliber, and maximum thickness was also conducted. The Pr > F .0001 suggests that the overall model is significant. Discriminant functions and canonical variables were obtained. Classification was first performed by using two values small and large calibers. The large caliber group consisted of .38, while the small caliber group included .22, .25, and .32. The correct classification rate using crossvalidation for large caliber is 86.96%, and 93.33% for the group small caliber. A narrower classification was also performed by using three values, .23 caliber (.22 and .25 calibers grouped), .32, and .38 as the criterion variable groups also using minimum diameter and maximum thickness as predictors. The correct classification rate using crossvalidation is 82.02% for .23 caliber, 73.94% for .38 caliber, and 16.67% for .32 caliber defects. The discriminant functions can be used with appropriate caution to classify observations into groups defined by caliber using minimum diameter and maximum thickness as the predictors. Caution is suggested when attempting to estimate caliber from defects that are not produced from the perpendicular entrance of a bullet.
长期以来，法医科学家一直摒弃通过入口创口来估计口径的方法。这似乎是法医病理学家从软组织角度出发得出的结果。本研究探讨了口径与颅骨入口创口及颅骨最大厚度之间的关系。本研究中考虑的口径有.22、.25、.32和.38。样本包括73个尸检标本（.22口径的37个、.25口径的5个、.32口径的6个、.38口径的25个）。为检验口径、最小直径和最大厚度之间关系的强度，进行了皮尔逊相关系数分析。观察到口径与最小直径之间的关系最为紧密。还观察到最小直径与最大厚度之间存在关系。为检验不同口径之间平均最小直径无显著差异这一零假设，进行了方差分析。方差分析得出因变量最小直径与口径之间存在紧密关系。还进行了测量最小直径、口径和最大厚度之间关联的多元回归分析。Pr > F.0001表明总体模型具有显著性。获得了判别函数和典型变量。首先通过使用两个值，即小口径和大口径进行分类。大口径组包括.38，而小口径组包括.22、.25和.32。使用交叉验证法，大口径组的正确分类率为86.96%，小口径组为93.33%。还通过使用三个值进行了更细致的分类，将.23口径（.22和.25口径合并）、.32和.38作为标准变量组，同样将最小直径和最大厚度作为预测变量。使用交叉验证法，.23口径的正确分类率为82.02%，.38口径为73.94%，.32口径创口为16.67%。判别函数可在适当谨慎的情况下用于将观察结果按照口径分类，以最小直径和最大厚度作为预测变量来定义组别。当试图从并非由子弹垂直射入产生的创口估计口径时，建议谨慎操作。
