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Main Authors: Wang, Jing, Shen, Jie, Xie, Qiaomin, Weiss, Jeremy C
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2602.02371
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author Wang, Jing
Shen, Jie
Xie, Qiaomin
Weiss, Jeremy C
author_facet Wang, Jing
Shen, Jie
Xie, Qiaomin
Weiss, Jeremy C
contents Estimating causal effects from longitudinal trajectories is central to understanding the progression of complex conditions and optimizing clinical decision-making, such as comorbidities and long COVID recovery. We introduce \emph{C-kNN--LSH}, a nearest-neighbor framework for sequential causal inference designed to handle such high-dimensional, confounded situations. By utilizing locality-sensitive hashing, we efficiently identify ``clinical twins'' with similar covariate histories, enabling local estimation of conditional treatment effects across evolving disease states. To mitigate bias from irregular sampling and shifting patient recovery profiles, we integrate neighborhood estimator with a doubly-robust correction. Theoretical analysis guarantees our estimator is consistent and second-order robust to nuisance error. Evaluated on a real-world Long COVID cohort with 13,511 participants, \emph{C-kNN-LSH} demonstrates superior performance in capturing recovery heterogeneity and estimating policy values compared to existing baselines.
format Preprint
id arxiv_https___arxiv_org_abs_2602_02371
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle C-kNN-LSH: A Nearest-Neighbor Algorithm for Sequential Counterfactual Inference
Wang, Jing
Shen, Jie
Xie, Qiaomin
Weiss, Jeremy C
Machine Learning
Estimating causal effects from longitudinal trajectories is central to understanding the progression of complex conditions and optimizing clinical decision-making, such as comorbidities and long COVID recovery. We introduce \emph{C-kNN--LSH}, a nearest-neighbor framework for sequential causal inference designed to handle such high-dimensional, confounded situations. By utilizing locality-sensitive hashing, we efficiently identify ``clinical twins'' with similar covariate histories, enabling local estimation of conditional treatment effects across evolving disease states. To mitigate bias from irregular sampling and shifting patient recovery profiles, we integrate neighborhood estimator with a doubly-robust correction. Theoretical analysis guarantees our estimator is consistent and second-order robust to nuisance error. Evaluated on a real-world Long COVID cohort with 13,511 participants, \emph{C-kNN-LSH} demonstrates superior performance in capturing recovery heterogeneity and estimating policy values compared to existing baselines.
title C-kNN-LSH: A Nearest-Neighbor Algorithm for Sequential Counterfactual Inference
topic Machine Learning
url https://arxiv.org/abs/2602.02371