Institute of Environmental Science and Research Limited, Auckland, New Zealand.
Department of Statistics, University of Auckland, Auckland, New Zealand.
J Forensic Sci. 2021 Nov;66(6):2138-2155. doi: 10.1111/1556-4029.14886. Epub 2021 Sep 22.
Likelihood ratios (LR) differences between the probabilistic genotyping software EuroForMix and STRmix™ are examined. After considering differences in the allele probabilities, the LRs from both software for an unambiguous single-source profile were identical (four significant figures). LRs from both software for an unambiguous single-source profile with alleles previously unseen in the allele frequency database (rare alleles) were the same (three significant figures) for θ = 0.01. Due to differences in the minimum allele frequencies, the LRs differed by three orders of magnitude when θ = 0. For both software, the LRs for a single-source dilution series decreased as the input amount decreased. The LRs from both software were within an order of magnitude for known contributors. The largest difference was where the target input amount was 0.0156 ng: The LR was 2.1 × 10 and the LR was 8.0 × 10 . Both software show similar LR behavior with respect to mixture ratio. For two person mixtures the LR increases for both the major and the minor as the ratio moves away from 1:1. The LR for the major stabilizes at about 3:1 whereas the LR for the minor reaches its maximum at about 3:1 and then declines. Greater differences in LR were observed between EuroForMix and STRmix™ for mixtures. One-hundred and twenty-nine mixtures from the PROVEDIt dataset were compared. LRs for 84% of the comparisons for known contributors without rare alleles were within two orders of magnitude. Five divergent results were investigated, and a manual intervention approach was applied where appropriate.
检验了概率基因分型软件 EuroForMix 和 STRmix™之间的似然比 (LR) 差异。在考虑了等位基因概率的差异后，两种软件对于明确的单一来源谱的 LR 是相同的（四位有效数字）。对于θ=0.01，两种软件对于在等位基因频率数据库中以前未见过的等位基因（稀有等位基因）的明确单一来源谱的 LR 相同（三位有效数字）。由于最小等位基因频率的差异，当θ=0 时，LR 相差三个数量级。对于两种软件，单一来源稀释系列的 LR 随着输入量的减少而降低。两种软件的 LR 对于已知贡献者都在一个数量级内。最大的差异出现在目标输入量为 0.0156ng 时：LR 为 2.1×10，LR 为 8.0×10。两种软件在混合比例方面表现出相似的 LR 行为。对于两个人的混合物，随着比例从 1:1 远离，主要和次要的 LR 都增加。主要的 LR 在大约 3:1 处稳定，而次要的 LR 在大约 3:1 处达到最大值，然后下降。在混合物中，EuroForMix 和 STRmix™ 之间观察到更大的 LR 差异。比较了来自 PROVEDIt 数据集的 129 种混合物。对于没有稀有等位基因的已知贡献者的 84%的比较，LR 都在两个数量级内。对五个分歧结果进行了调查，并在适当的情况下应用了手动干预方法。
