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Main Authors: Braun, Marc, Peña, Jose M., Daoud, Adel
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2508.01321
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author Braun, Marc
Peña, Jose M.
Daoud, Adel
author_facet Braun, Marc
Peña, Jose M.
Daoud, Adel
contents To reach human level intelligence, learning algorithms need to incorporate causal reasoning. But identifying causality, and particularly counterfactual reasoning, remains elusive. In this paper, we make progress on counterfactual inference in nonseparable outcome models by utilizing instrumental variables (IVs). IVs are a classic tool for mitigating bias from unobserved confounders when estimating causal effects. While IV methods for effect estimation have been extended to nonseparable outcome models under different assumptions, existing IV approaches to counterfactual prediction typically assume one-dimensional outcomes and additive noise. In this paper, we show that under standard IV assumptions, along with the assumption that the outcome function is invertible and has a triangular structure, then the treatment-outcome relationship becomes identifiable from observed data. We furthermore propose a method to learn the outcome function utilizing normalizing flows. This outcome function estimator can then be used to perform counterfactual inference. We refer to the method as Flow IV.
format Preprint
id arxiv_https___arxiv_org_abs_2508_01321
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Flow IV: Counterfactual Inference In Nonseparable Outcome Models Using Instrumental Variables
Braun, Marc
Peña, Jose M.
Daoud, Adel
Machine Learning
To reach human level intelligence, learning algorithms need to incorporate causal reasoning. But identifying causality, and particularly counterfactual reasoning, remains elusive. In this paper, we make progress on counterfactual inference in nonseparable outcome models by utilizing instrumental variables (IVs). IVs are a classic tool for mitigating bias from unobserved confounders when estimating causal effects. While IV methods for effect estimation have been extended to nonseparable outcome models under different assumptions, existing IV approaches to counterfactual prediction typically assume one-dimensional outcomes and additive noise. In this paper, we show that under standard IV assumptions, along with the assumption that the outcome function is invertible and has a triangular structure, then the treatment-outcome relationship becomes identifiable from observed data. We furthermore propose a method to learn the outcome function utilizing normalizing flows. This outcome function estimator can then be used to perform counterfactual inference. We refer to the method as Flow IV.
title Flow IV: Counterfactual Inference In Nonseparable Outcome Models Using Instrumental Variables
topic Machine Learning
url https://arxiv.org/abs/2508.01321