Caliber Estimation from Cranial Entrance Defect Measurements

Estimation of caliber from entrance defects has long been rejected by forensic scientists. However, previous studies have been from the viewpoint of the forensic pathologist, and because their focus is usually upon soft tissue, therefore this is a role for the forensic anthropologist to pursue. Consequently, 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 consists of 73 specimens obtained at autopsy (thirty-seven of .22 caliber, five of .25, six of .32, and twenty-five of .38). The strength of the relation between caliber, minimum diameter, and maximum thickness was tested by conducting a Pearson correlation coefficients. An analysis of variance procedure was performed to test the null hypothesis that the mean minimum diameter is not significantly different between calibers. In addition, a multiple regression analysis measuring the association between minimum diameter, caliber, and maximum thickness was conducted. Discriminant functions and canonical variables were obtained and presented.

This method cannot be used for exact caliber determination from cranial measurements. However, the discriminant functions can be used with caution to classify observations into groups defined by caliber using minimum diameter and maximum thickness as the predictors.