用贝叶斯模型分析尸体分解,精准推断死亡时间。
Modeling human decomposition: a Bayesian approach
- 构建贝叶斯生成模型,融合死亡后时间与环境/个体变量
- 24项分解特征预测AUC达0.85,死亡时间推断决定系数R²为71%
- 可整合专家经验,指导未来实验设计以获取更多知识
环境与个体变量以复杂方式影响人体分解速率,使基于分解特征估算死亡后时间(PMI)变得困难。本文提出一种生成式概率模型,基于PMI及广泛的环境与个体变量,对人类遗体分解过程进行建模。该模型明确表征各变量(包括PMI)对每项分解特征的影响,支持模型效应的直接解释,并可用于PMI推断与最优实验设计。模型通过贝叶斯方法拟合来自GeoFOR数据集的2,529个案例,结果表明其能准确预测24项分解特征,平均ROC AUC为0.85。利用贝叶斯反演技术,根据观察到的分解特征及环境、个体变量,推断出的PMI与真实值相关性达到R²=0.71。此外,我们展示了如何利用已拟合模型,基于期望信息增益框架设计未来实验,以最大化对分解机制的新认知。
原文摘要 · Abstract (English)
Environmental and individualistic variables affect the rate of human decomposition in complex ways. These effects complicate the estimation of the postmortem interval (PMI) based on observed decomposition characteristics. In this work, we develop a generative probabilistic model for decomposing human remains based on PMI and a wide range of environmental and individualistic variables. This model explicitly represents the effect of each variable, including PMI, on the appearance of each decomposition characteristic, allowing for direct interpretation of model effects and enabling the use of the model for PMI inference and optimal experimental design. In addition, the probabilistic nature of the model allows for the integration of expert knowledge in the form of prior distributions. We fit this model to a diverse set of 2,529 cases from the GeoFOR dataset. We demonstrate that the model accurately predicts 24 decomposition characteristics with an ROC AUC score of 0.85. Using Bayesian inference techniques, we invert the decomposition model to predict PMI as a function of the observed decomposition characteristics and environmental and individualistic variables, producing an R-squared measure of 71%. Finally, we demonstrate how to use the fitted model to design future experiments that maximize the expected amount of new information about the mechanisms of decomposition using the Expected Information Gain formalism.
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