Journal Published Online: 17 August 2005
Volume 50, Issue 5

A Large-Scale Statistical Analysis of Barefoot Impressions

CODEN: JFSCAS

Abstract

In an earlier paper, outlines of footprints of persons walking normally were studied to determine whether different people make verifiably distinct footprints. Our basic null hypothesis is: given a footprint outline trace made by Subject A (Alice), then Subject B (Bob), a distinct person, cannot produce a footprint outline trace indistinguishable from that of Alice. We showed in the previous work that the probability of a chance match is less than 10−8. In this paper we report two new advances in our research. First, we establish a rigorous mathematical framework for calculating worstcase and average chance-match probabilities. Second, we repeat the previous experiment to substantiate the earlier results, but with an expanded population sample size and a more representative and significantly bigger repeated sample. These improvements and a new automated tracing procedure for extracting all numerical measures lead to a sharpened accuracy with average chance match probabilities of 7.88 × 10−10 for a general population. In other words, the odds of a chance match are one in 1.27 billion.

Author Information

Kennedy, RB
Royal Canadian Mounted Police, Ottawa, Ontario, Canada
Chen, S
Statistics Canada, Ottawa, Ontario, Canada
Pressman, IS
Carleton University, Ottawa, Ontario, Canada
Yamashita, AB
Royal Canadian Mounted Police, Ottawa, Ontario, Canada
Pressman, AE
Carnegie Mellon Univ., Pittsburgh, PA
Pages: 10
Price: $25.00
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Stock #: JFS2004277
ISSN: 0022-1198
DOI: 10.1520/JFS2004277