为深度非参数Cox模型构建了可推断的相对风险估计理论
Beyond Consistency: Inference for the Relative risk functional in Deep Nonparametric Cox Models
- 基于梯度优化误差与样本内风险的非渐近界,建立泛化关系
- 通过结构化神经参数化实现点态偏差控制,支持渐近正态性
- 提出微小重抽样法,适用于真实方差衰减场景下的统计推断
深度神经网络在非参数Cox比例风险模型中的估计仍存在理论空白,尤其在部分似然下梯度优化误差如何传播至总体风险、点态偏差如何控制以支持有效推断,以及基于集成的不确定性量化在现实方差衰减条件下的表现尚不明确。本文建立了深度Cox估计器的渐近分布理论:首先,对一般训练网络建立了非渐近的Oracle不等式,将样本内优化误差与总体风险关联,无需精确经验风险最小化器;其次,设计一种结构化神经参数化,实现与Oracle界兼容的无穷范数逼近率,从而控制点态偏差;在该条件下,结合Hajek–Hoeffding投影,证明了子采样集成估计器的点态及多变量渐近正态性;推导出一组平衡偏差校正与投影主导性的子样本大小范围,其容忍单重叠协方差的衰减条件,弱于传统子采样文献假设;进一步通过微小重抽样表示提供解析协方差估计,并支持对相对风险对比(如对数风险比)的Wald型推断。最后,通过模拟和真实数据应用展示了该理论在有限样本下的影响。
原文摘要 · Abstract (English)
There remain theoretical gaps in deep neural network estimators for the nonparametric Cox proportional hazards model. In particular, it is unclear how gradient-based optimization error propagates to population risk under partial likelihood, how pointwise bias can be controlled to permit valid inference, and how ensemble-based uncertainty quantification behaves under realistic variance decay regimes. We develop an asymptotic distribution theory for deep Cox estimators that addresses these issues. First, we establish nonasymptotic oracle inequalities for general trained networks that link in-sample optimization error to population risk without requiring the exact empirical risk optimizer. We then construct a structured neural parameterization that achieves infinity-norm approximation rates compatible with the oracle bound, yielding control of the pointwise bias. Under these conditions and using the Hajek--Hoeffding projection, we prove pointwise and multivariate asymptotic normality for subsampled ensemble estimators. We derive a range of subsample sizes that balances bias correction with the requirement that the Hajek--Hoeffding projection remain dominant. This range accommodates decay conditions on the single-overlap covariance, which measures how strongly a single shared observation influences the estimator, and is weaker than those imposed in the subsampling literature. An infinitesimal jackknife representation provides analytic covariance estimation and valid Wald-type inference for relative risk contrasts such as log-hazard ratios. Finally, we illustrate the finite-sample implications of the theory through simulations and a real data application.
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