Advances in Fingerprint Technology.pdf

scores was then compared to the distribution of the 50,000 scores that resulted
from comparing each of the fingerprint images to itself. This was done by
assuming normal distributions and applying a sample Z score.
When examining the Z scores for the non-identical prints, Meagher,
Budowle, and Ziesig noted three comparisons with unusually high scores
(6.98, 6.95, and 3.41). Investigation of these comparisons led to the discovery
that they had resulted from comparisons of different prints from the same
finger. That is, within the data set of 50,000 prints, there had unintentionally
been included some rolled inked prints that had been made by the same
finger on different occasions. The three scores that were unusually high were
attributed to:
1. Comparing Print A of Individual 1 with Print B of Individual 1
2. Comparing Print B of Individual 1 with Print A of Individual 1
3. Comparing Print A of Individual 2 with Print B of Individual 2
From these results, it was apparent that another same-finger, different-print
comparison was in the set; namely:
4. Comparing Print B of Individual 2 with Print A of Individual 2
This comparison was subsequently found to have a Z score of 1.79, well in
among the scores of the non-identical prints. After discovery of these two pairs
of prints from the same fingers, these prints were excluded from the analysis.
Meagher, Budowle, and Ziesig proceeded by noting that the largest
remaining Z score for the non-identical print comparisons was 1.83 and that
the smallest Z score for the comparisons of the same print with itself (under
the hypothesis of equal means) was 21.7. For the two-sample test of means,
this Z score is associated with a probability of 1/10 97 ; thus, Meagher, Budowle,
and Ziesig concluded that the probability of a non-mate rolled fingerprint
being identical to any particular fingerprint was less than this value. They
went on to state that, given a world population of 5.9 × 10 9 , the approximate
chance of any two rolled fingerprints on Earth being identical was 59/10 88 , a
value obtained by multiplying their original probability by the world finger
population.
The Second Experiment, Based on Comparing Subsets of the
Records with the Same Complete Records
The second experiment conducted by Meagher, Budowle, and Ziesig closely
followed the first, but simulated latent prints, constructed from the 50,000
prints, were used to compare against the same set of 50,000 prints. To construct
the simulated latent prints, the central 21.7% of the whole rolled