DEM: A Distilled Explanation Model for Interpretable Anomaly Detection in Physiological Sensor Networks
DEM:面向生理传感器网络中可解释异常检测的蒸馏解释模型
Jyotirmoy Singh, Anushka Roy, Shreea Bose, Chittaranjan Hota
AI总结 提出一种三阶段玻璃箱框架DEM,通过将梯度提升专家模型的知识蒸馏到基于线性基线残差的决策树中,实现高精度与内在可解释性的异常检测,并引入蒸馏保真度指标量化解释可信度。
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- 21 pages, 10 figures, 7 tables. Code: https://github.com/Jyotirmoy17/dem-model
无线体域网(WBANs)中生理传感器数据的异常检测可能由传感器故障、网络中断或数据缺失引起,导致误报。因此,它既需要高预测精度,也需要临床可解释的解释。现有方法要么依赖性能强但无透明度的黑盒模型,要么依赖SHAP和LIME等事后解释方法。本文提出蒸馏解释模型(DEM),一个三阶段玻璃箱框架,将梯度提升专家模型的非线性知识蒸馏到基于线性基线残差的可解释决策树中,使得解释不是近似而是预测本身。DEM引入了一种新颖的蒸馏保真度指标,量化解释树忠实捕捉专家模型非线性贡献的程度,提供了先前可解释模型所缺乏的解释可信度的原则性度量。在包括MIMIC-IV、WESAD、eICU和内部SmartNet WBAN语料库在内的四个生理数据集上评估,DEM在临床上下文异常检测上达到0.9964的AUC,在可穿戴压力检测上达到0.9047,同时以可控深度生成人类可读的if-then规则。推理每1000个样本需要0.17ms,使DEM比基于SHAP的事后解释快1235倍,适用于实时生理监测。消融研究证实,XGBoost蒸馏步骤比朴素残差拟合提供了可测量的增益,深度敏感性分析展示了DEM在现有内在可解释模型中独有的、用户可控的准确性-可解释性权衡。
Anomaly detection in physiological sensor data from Wireless Body Area Networks (WBANs) can be caused by sensor faults, network disruptions, or missing data, leading to false alarms. Hence, it demands both high predictive accuracy and clinically interpretable explanations. Existing approaches rely either on black-box models that achieve strong performance but offer no transparency, or on post-prediction explanation methods such as SHAP and LIME. In this paper, we propose the Distilled Explanation Model (DEM), a three-stage glass-box framework that distills the non-linear knowledge of a gradient boosting expert into an interpretable decision tree operating on residuals relative to a linear baseline, so that the explanation is not an approximation but the prediction itself. DEM introduces a novel distillation fidelity metric that quantifies how faithfully the explanation tree captures the expert model's non-linear contribution, providing a principled measure of explanation trustworthiness absent from prior interpretable models. Evaluated across four physiological datasets, including MIMIC-IV, WESAD, eICU, and an in-house SmartNet WBAN corpus, DEM achieves an AUC of 0.9964 on clinical contextual anomaly detection and 0.9047 on wearable stress detection while producing human-readable if-then rules at a controllable depth. Inference requires 0.17ms per 1000 samples, rendering DEM 1235x faster than SHAP-based post-hoc explanation and suitable for real-time physiological monitoring. Ablation studies confirm that the XGBoost distillation step provides measurable gains over naive residual fitting, and depth-sensitivity analysis demonstrates an explicit, user-controlled accuracy-interpretability trade-off unique to DEM among existing intrinsically interpretable models.