ATTEMPT AT DETERMINING PROBABILITIES IN HUMAN SCALP HAIR COMPARISON

• NCJ Number: 16725
• Journal: Journal of Forensic Sciences Volume: 19 Issue: 3 Dated: (JULY 1974) Pages: 599-606
• Author(s): B D GAUDETTE; E S KEEPING
• Date Published: 1974
• Length: 8 pages
• Corporate Author: American Soc for Testing and Materials
• Publication Format: Article
• Publication Type: Statistics
• Language: English
• Country: United States of America
• Note: *This document is currently unavailable from NCJRS.

Annotation

A SYSTEM FOR CODING THE MACROSCOPIC AND MICROSCOPIC CHARACTERISTICS OF HUMAN SCALP HAIR IS PRESENTED AND A STATISTICAL ANALYSIS OF THE PROBABILITIES INVOLVED IN HUMAN HAIR COMPARISON IS CARRIED OUT.

Abstract

BY USE OF A CARD CODING SYSTEM FOR SOME MACROSCOPIC AND MICROSCOPIC CHARACTERISTICS OF HUMAN SCALP HAIRS, 366,630 COMPARISONS WERE MADE BETWEEN 861 HAIRS FROM 100 DIFFERENT INDIVIDUALS. OF THESE, NINE PAIRS WERE FOUND TO BE INDISTINGUISHABLE. IT IS ESTIMATED THAT IF ONE HUMAN SCALP HAIR FOUND AT THE SCENE OF A CRIME IS INDISTINGUISHABLE FROM AT LEAST ONE OF A GROUP OF ABOUT NINE DISSIMILAR HAIRS FROM A GIVEN SOURCE, THE PROBABILITY THAT IT COULD HAVE ORIGINATED FROM ANOTHER SOURCE IS VERY SMALL, ABOUT 1 IN 4500. IF, INSTEAD OF ONE HAIR, N MUTUALLY DISSIMILAR HUMAN SCALP HAIRS ARE FOUND TO BE INDISTINGUISHABLE FROM THOSE OF A GIVEN SOURCE, THIS PROBABILITY IS THEN ESTIMATED TO BE (1/4500) TO THE NTH POWER, WHICH IS NEGLIGIBLE WHEN N IS GREATER THAN OR EQUAL TO THREE. (AUTHOR ABSTRACT)