Gender identification from thumbprint ridge thickness among Hausa population of Nigeria using likelihood ratio and posterior probability density

Abstract

The objectives of the present study were to identify gender from  thumbprints ridge thickness using likelihood ratio and posterior probability density as well as to determine which of the three areas of thumb has more potential in sex determination. Ridge thickness for 97 male and 97 female subjects within the age range of 18-25 years were examined within the 25 mm² areas of the ulnar, radial and proximal parts of the thumb making up 1164 areas of the thumbprints. Female subjects exhibited finer ridge count compared to males in ulnar area of both sides of the thumbs. In the radial area, females were found to have finer ridge counts as in ulnar side, but with some coarse ridge. For the right proximal ridge thickness, a similar  trend to that in the radial area was noticed, however, in the left thumbprint, males tend to have finer ridge counts compared to females. It was noticed that chance of sex inference from likelihood ratio decreased in the following order: proximal ridge thickness < radial ridge thickness < ulnar ridge  thickness as ridge thickness decreases in favor of females but left proximal ridge thickness showed increased in likelihood ratio as ridge thickness decreased in favor of males. Ridge thickness in ulnar area showed more discrimination power compared to the other two areas studied. Considering equal probability for each sex, likelihood ratio reveals the applicability of ridge thickness in sex inference among Hausa population.

Keywords: Forensic sciences, likelihood ratio, Hausa population, ridge thickness, sex inference.