U.S. flag

An official website of the United States government, Department of Justice.

NCJRS Virtual Library

The Virtual Library houses over 235,000 criminal justice resources, including all known OJP works.
Click here to search the NCJRS Virtual Library

Using Automated Comparisons to Quantify Handwriting Individuality

NCJ Number
Journal of Forensic Sciences Volume: 56 Issue: 3 Dated: May 2011 Pages: 683-689
Christopher P. Saunders, Ph.D.; Linda J. Davis, Ph.D.; JoAnn Buscaglia, Ph.D.
Date Published
May 2011
7 pages
The goal of this paper is to illustrate what can be stated about the individuality of writing profiles using a database of handwriting samples and an automated comparison procedure.
The proposition that writing profiles are unique is considered a key premise underlying forensic handwriting comparisons. An empirical study cannot validate this proposition because of the impossibility of observing sample documents written by every individual. This paper provides a strategy for bounding the probability of observing two writers with indistinguishable writing profiles (regardless of the comparison methodology used) with a random match probability that can be estimated statistically. The computation of this bound is illustrated using a convenience sample of documents and an automated comparison procedure based on Pearson's chi-squared statistic applied to frequency distributions of letter shapes extracted from handwriting samples. The study also shows how this bound can be used when designing an empirical study of individuality. (Published Abstract)