Journal article

Decision-making in familial database searching: KI alone or not alone?

David J Balding, Michael Krawczak, John S Buckleton, James M Curran



We consider the comparison of hypotheses "parent-child" or "full siblings" against the alternative of "unrelated" for pairs of individuals for whom DNA profiles are available. This is a situation that occurs repeatedly in familial database searching. A decision rule that uses both the kinship index (KI), also known as the likelihood ratio, and the identity-by-state statistic (IBS) was advocated in a recent report as superior to the use of KI alone. Such proposal appears to conflict with the Neyman-Pearson Lemma of statistics, which states that the likelihood ratio alone provides the most powerful criterion for distinguishing between any two simple hypotheses. We therefore performed a simulat..

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University of Melbourne Researchers


Awarded by US National Institute of Justice

Funding Acknowledgements

We gratefully acknowledge the comments of Lisa Melia, Michael Taylor, and two anonymous referees which greatly improved this paper. We would also like to acknowledge the assistance of Torben Tvedebrink whose help was invaluable in the validation and verification of the software. This work was supported in part by 136 grant 2011-DN-BX-K541 from the US National Institute of Justice.