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Estimating trace-suspect match probabilities in forensics for singleton Y-STR haplotypes using coalescent theory

Presented by: 
Amke Caliebe Christian-Albrechts-Universität zu Kiel
Thursday 10th November 2016 -
10:15 to 11:00
INI Seminar Room 1
Estimation of match probabilities for singleton haplotypes of lineage markers, i.e. for haplotypes observed only once in a reference database augmented by a suspect profile, is an important problem in forensic genetics. We compared the performance of four estimators of singleton match probabilities for Y-STRs, namely the count estimator, both with and without Brenner’s so-called kappa correction, the surveying estimator, and a previously proposed, but rarely used, coalescent-based approach implemented in the BATWING software. Extensive simulation with BATWING of the underlying population history, haplotype evolution and subsequent database sampling revealed that the coalescent-based approach and Brenner’s estimator are characterized by lower bias and lower mean squared error than the other two estimators. Moreover, in contrast to the two count estimators, both the surveying and the coalescent-based approach exhibited a good correlation between the estimated and true match probabilities. However, although its overall performance is thus better than that of any other recognized method, the coalescent-based estimator is still very computation-intense. Its application in forensic practice therefore will have to be limited to small reference databases, or to isolated cases of particular interest, until more powerful algorithms for coalescent simulation have become available.

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Presentation Material: 
University of Cambridge Research Councils UK
    Clay Mathematics Institute London Mathematical Society NM Rothschild and Sons