Slooten K
Netherlands Forensic Institute, P.O. Box 24044, 2490 AA The Hague, The Netherlands; VU University Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands.
Forensic Sci Int Genet. 2017 Jan;26:40-47. doi: 10.1016/j.fsigen.2016.10.003. Epub 2016 Oct 12.
Several methods exist to compute the likelihood ratio LR(M, g) evaluating the possible contribution of a person of interest with genotype g to a mixed trace M. In this paper we generalize this LR to a likelihood ratio LR(M, M) involving two possibly mixed traces M and M, where the question is whether there is a donor in common to both traces. In case one of the traces is in fact a single genotype, then this likelihood ratio reduces to the usual LR(M, g). We explain how our method conceptually is a logical consequence of the fact that LR calculations of the form LR(M, g) can be equivalently regarded as a probabilistic deconvolution of the mixture. Based on simulated data, and using a semi-continuous mixture evaluation model, we derive ROC curves of our method applied to various types of mixtures. From these data we conclude that searches for a common donor are often feasible in the sense that a very small false positive rate can be combined with a high probability to detect a common donor if there is one. We also show how database searches comparing all traces to each other can be carried out efficiently, as illustrated by the application of the method to the mixed traces in the Dutch DNA database.
存在多种方法来计算似然比LR(M, g)，以评估基因型为g的目标个体对混合痕迹M可能的贡献。在本文中，我们将此似然比推广为涉及两个可能的混合痕迹M和M的似然比LR(M, M)，其中问题在于这两个痕迹是否有共同的供体。如果其中一个痕迹实际上是单一基因型，那么这个似然比就简化为通常的LR(M, g)。我们解释了我们的方法在概念上如何是这样一个事实的逻辑结果，即形式为LR(M, g)的似然比计算可以等效地视为混合物的概率解卷积。基于模拟数据，并使用半连续混合评估模型，我们推导了应用于各种类型混合物的我们方法的ROC曲线。从这些数据中我们得出结论，在可以将非常低的假阳性率与如果存在共同供体则以高概率检测到该供体的意义上，寻找共同供体通常是可行的。我们还展示了如何有效地进行将所有痕迹相互比较的数据库搜索，如将该方法应用于荷兰DNA数据库中的混合痕迹所说明的那样。
