Abstract
Although the likelihood ratio is a well-known statistical technique, commercial off-the-shelf
(COTS) software products for its calculation are not sufficiently validated to suit
general requirements for the competence of testing and calibration laboratories (EN/ISO/IEC
17025:2005 norm) per se. The software in question can be considered critical as it directly weighs the forensic
evidence allowing judges to decide on guilt or innocence or to identify person or
kin (i.e.: in mass fatalities). For these reasons, accredited laboratories shall validate
likelihood ratio software in accordance with the above norm.
To validate software for calculating the likelihood ratio in parentage/kinship scenarios
I assessed available vendors, chose two programs (Paternity Index and familias) for testing, and finally validated them using tests derived from elaboration of
the available guidelines for the field of forensics, biomedicine, and software engineering.
MS Excel calculation using known likelihood ratio formulas or peer-reviewed results
of difficult paternity cases were used as a reference.
Using seven testing cases, it was found that both programs satisfied the requirements
for basic paternity cases. However, only a combination of two software programs fulfills
the criteria needed for our purpose in the whole spectrum of functions under validation
with the exceptions of providing algebraic formulas in cases of mutation and/or silent
allele.
Keywords
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Article info
Publication history
Published online: December 25, 2008
Accepted:
November 17,
2008
Received in revised form:
September 19,
2008
Received:
July 31,
2008
Identification
Copyright
© 2008 Elsevier Ireland Ltd. Published by Elsevier Inc. All rights reserved.
