Late Fusion Multi-task Learning for Semiparametric Inference with Nuisance Parameters

Fuente: arXiv
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Autori principali: Bhattacharya, Sohom, Chen, Yongzhuo, Liang, Muxuan
Natura: Preprint
Pubblicazione: 2025
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author Bhattacharya, Sohom
Chen, Yongzhuo
Liang, Muxuan
author_facet Bhattacharya, Sohom
Chen, Yongzhuo
Liang, Muxuan
contents In the age of large and heterogeneous datasets, the integration of information from diverse sources is essential to improve parameter estimation. Multi-task learning offers a powerful approach by enabling simultaneous learning across related tasks. In this work, we introduce a late fusion framework for multi-task learning with semiparametric models that involve infinite-dimensional nuisance parameters, focusing on applications such as heterogeneous treatment effect estimation across multiple data sources, including electronic health records from different hospitals or clinical trial data. Our framework is two-step: first, initial double machine-learning estimators are obtained through individual task learning; second, these estimators are adaptively aggregated to exploit task similarities while remaining robust to task-specific differences. In particular, the framework avoids individual level data sharing, preserving privacy. Additionally, we propose a novel multi-task learning method for nuisance parameter estimation, which further enhances parameter estimation when nuisance parameters exhibit similarity across tasks. We establish theoretical guarantees for the method, demonstrating faster convergence rates compared to individual task learning when tasks share similar parametric components. Extensive simulations and real data applications complement the theoretical findings of our work while highlight the effectiveness of our framework even in moderate sample sizes.
format Preprint
id arxiv_https___arxiv_org_abs_2507_07941
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Late Fusion Multi-task Learning for Semiparametric Inference with Nuisance Parameters
Bhattacharya, Sohom
Chen, Yongzhuo
Liang, Muxuan
Methodology
Machine Learning
In the age of large and heterogeneous datasets, the integration of information from diverse sources is essential to improve parameter estimation. Multi-task learning offers a powerful approach by enabling simultaneous learning across related tasks. In this work, we introduce a late fusion framework for multi-task learning with semiparametric models that involve infinite-dimensional nuisance parameters, focusing on applications such as heterogeneous treatment effect estimation across multiple data sources, including electronic health records from different hospitals or clinical trial data. Our framework is two-step: first, initial double machine-learning estimators are obtained through individual task learning; second, these estimators are adaptively aggregated to exploit task similarities while remaining robust to task-specific differences. In particular, the framework avoids individual level data sharing, preserving privacy. Additionally, we propose a novel multi-task learning method for nuisance parameter estimation, which further enhances parameter estimation when nuisance parameters exhibit similarity across tasks. We establish theoretical guarantees for the method, demonstrating faster convergence rates compared to individual task learning when tasks share similar parametric components. Extensive simulations and real data applications complement the theoretical findings of our work while highlight the effectiveness of our framework even in moderate sample sizes.
title Late Fusion Multi-task Learning for Semiparametric Inference with Nuisance Parameters
topic Methodology
Machine Learning
url https://arxiv.org/abs/2507.07941