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SUMMARY:Empirical support for DNA match probabilities - James Curran (Auck
 land)
DTSTART:20091119T160000Z
DTEND:20091119T170000Z
UID:TALK20012@talks.cam.ac.uk
CONTACT:Richard Nickl
DESCRIPTION:Is there a problem with the models used to estimate DNA match 
 probabilities (or likelihood ratios)?  For years\, eminent scientists have
  complained that\nthe estimates of the tiny frequencies of DNA types are u
 nfounded. Compounding this are reports of shocking numbers of "partial mat
 ches" among samples\nwithin large DNA databases\, and some scientists have
  complained that the infinitesimal figures used in court to estimate the p
 robability of a random\nmatch are no better than alchemy [1]. Obviously su
 ch findings and statements damage the public perception of the credibility
  of DNA statistics.\n\nCloser inspection of this problem\, however\, revea
 ls that this behaviour\nis expected. Weir [2\, 3] showed that this problem
  is equivalent to the classic "birthday" problem in statistics\, and that 
 the solution can be used to\nexplain (some of) the complete matches. Weir 
 also showed that there is additional information in the partial matches. I
 t is possible to calculate the\nexpected values for the partial matches as
  well as the complete matches\, and with this information we can see how w
 ell our observations conform to this\nexpectation.\n\nIn this talk I will 
 discuss Weir's solution and a proposed extension [4]\nwhich allows for the
  fact that any sizeable modern DNA database is likely to contain pairs of 
 people who are full siblings (brothers)\, first cousins or\nparents/childr
 en.\n\nReferences\n[1] David H. Kaye. Trawling DNA databases for partial m
 atches: What is\nthe FBI afraid of? Cornell Journal of Law and Public Poli
 cy\, In Press\,\n2009.\n[2] Bruce S Weir. Matching and partially-matching 
 DNA profiles. Journal of Forensic Sciences\, 49(5):1009{1014\, September 2
 004. PMID: 15461102.\n[3] Bruce S. Weir. The rarity of DNA profiles. The A
 nnals of Applied\nStatistics\, 1(2):358{370\, 2007.\n[4] James M. Curran\,
  Simon J. Walsh\, and John Buckleton. Empirical\ntesting of estimated DNA 
 frequencies. Forensic Science International:\nGenetics\, 1(3-4):267{272\, 
 December 2007.\n
LOCATION:MR12\, CMS\, Wilberforce Road\, Cambridge\, CB3 0WB
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