Pseudo-Labeling for Kernel Ridge Regression under Covariate Shift

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1. Verfasser: Wang, Kaizheng
Format: Preprint
Veröffentlicht: 2023
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_version_ 1866912498481889280
author Wang, Kaizheng
author_facet Wang, Kaizheng
contents We develop and analyze a principled approach to kernel ridge regression under covariate shift. The goal is to learn a regression function with small mean squared error over a target distribution, based on unlabeled data from there and labeled data that may have a different feature distribution. We propose to split the labeled data into two subsets, and conduct kernel ridge regression on them separately to obtain a collection of candidate models and an imputation model. We use the latter to fill the missing labels and then select the best candidate accordingly. Our non-asymptotic excess risk bounds demonstrate that our estimator adapts effectively to both the structure of the target distribution and the covariate shift. This adaptation is quantified through a notion of effective sample size that reflects the value of labeled source data for the target regression task. Our estimator achieves the minimax optimal error rate up to a polylogarithmic factor, and we find that using pseudo-labels for model selection does not significantly hinder performance.
format Preprint
id arxiv_https___arxiv_org_abs_2302_10160
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Pseudo-Labeling for Kernel Ridge Regression under Covariate Shift
Wang, Kaizheng
Methodology
Machine Learning
Statistics Theory
62J07, 62G05
We develop and analyze a principled approach to kernel ridge regression under covariate shift. The goal is to learn a regression function with small mean squared error over a target distribution, based on unlabeled data from there and labeled data that may have a different feature distribution. We propose to split the labeled data into two subsets, and conduct kernel ridge regression on them separately to obtain a collection of candidate models and an imputation model. We use the latter to fill the missing labels and then select the best candidate accordingly. Our non-asymptotic excess risk bounds demonstrate that our estimator adapts effectively to both the structure of the target distribution and the covariate shift. This adaptation is quantified through a notion of effective sample size that reflects the value of labeled source data for the target regression task. Our estimator achieves the minimax optimal error rate up to a polylogarithmic factor, and we find that using pseudo-labels for model selection does not significantly hinder performance.
title Pseudo-Labeling for Kernel Ridge Regression under Covariate Shift
topic Methodology
Machine Learning
Statistics Theory
62J07, 62G05
url https://arxiv.org/abs/2302.10160