On the Equivalence between Neyman Orthogonality and Pathwise Differentiability

Fuente: arXiv
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Autores principales: Chen, Yuxi, Kennedy, Edward H., Balakrishnan, Sivaraman
Formato: Preprint
Publicado: 2026
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author Chen, Yuxi
Kennedy, Edward H.
Balakrishnan, Sivaraman
author_facet Chen, Yuxi
Kennedy, Edward H.
Balakrishnan, Sivaraman
contents It has been frequently observed that Neyman orthogonality, the central device underlying double/debiased machine learning (Chernozhukov et al., 2018), and pathwise differentiability, a cornerstone concept from semiparametric theory, often lead to the same debiased estimators in practice. Despite the widespread adoption of both ideas, the precise nature of this equivalence has remained elusive, with the two concepts having been developed in largely separate traditions. In this work, we revisit the semiparametric framework of van der Laan and Robins (2003) and identify an implicit regularity assumption on the relationship between target and nuisance parameters -- a local product structure -- that allows us to establish a formal equivalence between Neyman orthogonality and pathwise differentiability. We also show that the two directions of this equivalence impose fundamentally different structural requirements. Finally, we illustrate the theory through three detailed examples of estimating the average treatment effect and expected density in a nonparametric model, as well as the slope in a partially linear model. This helps clarify the relationship between these two foundational frameworks and provides a useful reference for practitioners working at their intersection.
format Preprint
id arxiv_https___arxiv_org_abs_2603_15817
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle On the Equivalence between Neyman Orthogonality and Pathwise Differentiability
Chen, Yuxi
Kennedy, Edward H.
Balakrishnan, Sivaraman
Methodology
Statistics Theory
It has been frequently observed that Neyman orthogonality, the central device underlying double/debiased machine learning (Chernozhukov et al., 2018), and pathwise differentiability, a cornerstone concept from semiparametric theory, often lead to the same debiased estimators in practice. Despite the widespread adoption of both ideas, the precise nature of this equivalence has remained elusive, with the two concepts having been developed in largely separate traditions. In this work, we revisit the semiparametric framework of van der Laan and Robins (2003) and identify an implicit regularity assumption on the relationship between target and nuisance parameters -- a local product structure -- that allows us to establish a formal equivalence between Neyman orthogonality and pathwise differentiability. We also show that the two directions of this equivalence impose fundamentally different structural requirements. Finally, we illustrate the theory through three detailed examples of estimating the average treatment effect and expected density in a nonparametric model, as well as the slope in a partially linear model. This helps clarify the relationship between these two foundational frameworks and provides a useful reference for practitioners working at their intersection.
title On the Equivalence between Neyman Orthogonality and Pathwise Differentiability
topic Methodology
Statistics Theory
url https://arxiv.org/abs/2603.15817