arXiv:2608.25930stat.MEcs.CV2026-08

提出新方法控制深度学习中的遗漏变量偏差,提升模型公平性与可解释性。

Controlling for Omitted Variable Bias in Deep Neural Networks

论文配图:Controlling for Omitted Variable Bias in Deep Neural Networks
图 1 · 摘自论文原文
  • 基于广义加性模型引入控制变量,重构预训练网络的输出层。
  • 通过交叉拟合与岭正则化实现稳定估计,准确恢复真实效应。
  • 适用于需消除混淆因素影响的医学影像等高风险场景。

在统计建模中,控制变量常用于处理已知混杂因素带来的遗漏变量偏差。然而,在深度学习中这一方法仍被忽视。尽管深度模型会隐式编码与结果相关的图像可推断协变量(如人口统计信息),导致“捷径学习”形式的遗漏变量偏差,现有多数公平性或混杂控制方法仅限制协变量与预测的相关性,却无法真正纠正偏差。本文提出一种基于广义加性模型的深度学习控制变量方法,通过重新拟合预训练网络的最后层,引入协变量效应,并采用交叉拟合与岭正则化避免共线性问题。我们进一步提出对协变量效应进行正交化处理以排除中介效应,并对协变量分布进行边际化以控制其影响。该方法可生成无偏且可解释的预测结果,灵活适应不同科学或公平目标。我们在模拟图像数据上验证了该方法能一致估计真实效应,优于现有方法。在含实验性混淆的真实神经影像数据上,该方法将预测性能恢复至未受干扰模型的水平。代码已开源:https://github.com/mpff/cocodeel。

原文摘要 · Abstract (English)

Control variables are widely used in statistical modelling to account for omitted variable bias of known confounders. However, they have largely been underexplored in deep learning. This is surprising, given that deep learning models encode image-inferable covariates, such as demographic variables, into their predictions when these covariates are correlated with the outcome---a form of omitted variable bias referred to as 'shortcut learning'. While many existing confound-control or fairness methods try to restrict the correlation of such covariates with model predictions, we show that this fails to correct for omitted variable bias. We therefore propose a control variable approach for deep learning models, based on generalised additive modelling of the effects of model inputs and covariates. As flexible additive models can suffer from concurvity, we introduce an estimation procedure that refits the final layer of a pre-trained network to include covariate effects, using cross-fitting with ridge penalisation. We show how these effects can be orthogonalised with respect to covariates to exclude their mediated effects and that model predictions can be marginalised over the covariate distribution to control for their effect. This yields unbiased, interpretable predictions and offers flexibility to model the desired effects depending on the scientific or fairness objective. We verify our approach using simulated images, and demonstrate consistent estimation of true effects. Existing methods either require more data or fail to recover the true effects. We apply our method to real neuroimaging data with experimentally induced confounding, where it recovers prediction performance to near the level of a model trained on unconfounded data. Code is available at https://github.com/mpff/cocodeel.

深度学习偏差控制公平性神经影像

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