Overlap-Adaptive Regularization for Conditional Average Treatment Effect Estimation

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Hauptverfasser: Melnychuk, Valentyn, Frauen, Dennis, Schweisthal, Jonas, Feuerriegel, Stefan
Format: Preprint
Veröffentlicht: 2025
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author Melnychuk, Valentyn
Frauen, Dennis
Schweisthal, Jonas
Feuerriegel, Stefan
author_facet Melnychuk, Valentyn
Frauen, Dennis
Schweisthal, Jonas
Feuerriegel, Stefan
contents The conditional average treatment effect (CATE) is widely used in personalized medicine to inform therapeutic decisions. However, state-of-the-art methods for CATE estimation (so-called meta-learners) often perform poorly in the presence of low overlap. In this work, we introduce a new approach to tackle this issue and improve the performance of existing meta-learners in the low-overlap regions. Specifically, we introduce Overlap-Adaptive Regularization (OAR) that regularizes target models proportionally to overlap weights so that, informally, the regularization is higher in regions with low overlap. To the best of our knowledge, our OAR is the first approach to leverage overlap weights in the regularization terms of the meta-learners. Our OAR approach is flexible and works with any existing CATE meta-learner: we demonstrate how OAR can be applied to both parametric and non-parametric second-stage models. Furthermore, we propose debiased versions of our OAR that preserve the Neyman-orthogonality of existing meta-learners and thus ensure more robust inference. Through a series of (semi-)synthetic experiments, we demonstrate that our OAR significantly improves CATE estimation in low-overlap settings in comparison to constant regularization.
format Preprint
id arxiv_https___arxiv_org_abs_2509_24962
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Overlap-Adaptive Regularization for Conditional Average Treatment Effect Estimation
Melnychuk, Valentyn
Frauen, Dennis
Schweisthal, Jonas
Feuerriegel, Stefan
Machine Learning
The conditional average treatment effect (CATE) is widely used in personalized medicine to inform therapeutic decisions. However, state-of-the-art methods for CATE estimation (so-called meta-learners) often perform poorly in the presence of low overlap. In this work, we introduce a new approach to tackle this issue and improve the performance of existing meta-learners in the low-overlap regions. Specifically, we introduce Overlap-Adaptive Regularization (OAR) that regularizes target models proportionally to overlap weights so that, informally, the regularization is higher in regions with low overlap. To the best of our knowledge, our OAR is the first approach to leverage overlap weights in the regularization terms of the meta-learners. Our OAR approach is flexible and works with any existing CATE meta-learner: we demonstrate how OAR can be applied to both parametric and non-parametric second-stage models. Furthermore, we propose debiased versions of our OAR that preserve the Neyman-orthogonality of existing meta-learners and thus ensure more robust inference. Through a series of (semi-)synthetic experiments, we demonstrate that our OAR significantly improves CATE estimation in low-overlap settings in comparison to constant regularization.
title Overlap-Adaptive Regularization for Conditional Average Treatment Effect Estimation
topic Machine Learning
url https://arxiv.org/abs/2509.24962