Institute of Environmental Science and Research Limited, Private Bag 92021, Auckland 1142 New Zealand.
Institute of Environmental Science and Research Limited, Private Bag 92021, Auckland 1142 New Zealand.
Forensic Sci Int Genet. 2023 Sep;66:102913. doi: 10.1016/j.fsigen.2023.102913. Epub 2023 Jul 11.
Evidential value of DNA mixtures is typically expressed by a likelihood ratio. However, selecting appropriate propositions can be contentious, because assumptions may need to be made around, for example, the contribution of a complainant's profile, or relatedness between contributors. A choice made one way or another disregards any uncertainty that may be present about such an assumption. To address this, a complex proposition that considers multiple sub-propositions with different assumptions may be more appropriate. While the use of complex propositions has been advocated in the literature, the uptake in casework has been limited. We provide a mathematical framework for evaluating DNA evidence given complex propositions and discuss its implementation in the DBLR™ software. The software simultaneously handles multiple mixed samples, reference profiles and relationships as described by a pedigree, which unlocks a variety of applications. We provide several examples to illustrate how complex propositions can efficiently evaluate DNA evidence. The addition of this feature to DBLR™ provides a tool to approach the long-accepted, but often impractical suggestion that propositions should be exhaustive within a case context.
DNA 混合物的证据价值通常通过似然比来表示。然而，选择合适的命题可能存在争议，因为可能需要围绕投诉人的特征贡献或贡献者之间的相关性等问题做出假设。无论选择哪种方式，都会忽略这种假设可能存在的任何不确定性。为了解决这个问题，考虑具有不同假设的多个子命题的复杂命题可能更为合适。尽管文献中提倡使用复杂命题，但在案例工作中的应用却很有限。我们提供了一个用于评估给定复杂命题的 DNA 证据的数学框架，并讨论了它在 DBLR™软件中的实现。该软件可以同时处理多个混合样本、参考特征以及由系谱描述的关系，从而解锁了各种应用。我们提供了几个示例来说明如何有效地使用复杂命题来评估 DNA 证据。将此功能添加到 DBLR™中提供了一种工具，可以解决长期以来被接受但通常不切实际的建议，即命题应在案件背景下详尽无遗。
