Ridge Boosting is Both Robust and Efficient

Fuente: arXiv
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Main Authors: Bruns-Smith, David, Xie, Zhongming, Feller, Avi
Format: Preprint
Published: 2025
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author Bruns-Smith, David
Xie, Zhongming
Feller, Avi
author_facet Bruns-Smith, David
Xie, Zhongming
Feller, Avi
contents Estimators in statistics and machine learning must typically trade off between efficiency, having low variance for a fixed target, and distributional robustness, such as multiaccuracy, or having low bias over a range of possible targets. In this paper, we consider a simple estimator, ridge boosting: starting with any initial predictor, perform a single boosting step with (kernel) ridge regression. Surprisingly, we show that ridge boosting simultaneously achieves both efficiency and distributional robustness: for target distribution shifts that lie within an RKHS unit ball, this estimator maintains low bias across all such shifts and has variance at the semiparametric efficiency bound for each target. In addition to bridging otherwise distinct research areas, this result has immediate practical value. Since ridge boosting uses only data from the source distribution, researchers can train a single model to obtain both robust and efficient estimates for multiple target estimands at the same time, eliminating the need to fit separate semiparametric efficient estimators for each target. We assess this approach through simulations and an application estimating the age profile of retirement income.
format Preprint
id arxiv_https___arxiv_org_abs_2510_22083
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Ridge Boosting is Both Robust and Efficient
Bruns-Smith, David
Xie, Zhongming
Feller, Avi
Methodology
Estimators in statistics and machine learning must typically trade off between efficiency, having low variance for a fixed target, and distributional robustness, such as multiaccuracy, or having low bias over a range of possible targets. In this paper, we consider a simple estimator, ridge boosting: starting with any initial predictor, perform a single boosting step with (kernel) ridge regression. Surprisingly, we show that ridge boosting simultaneously achieves both efficiency and distributional robustness: for target distribution shifts that lie within an RKHS unit ball, this estimator maintains low bias across all such shifts and has variance at the semiparametric efficiency bound for each target. In addition to bridging otherwise distinct research areas, this result has immediate practical value. Since ridge boosting uses only data from the source distribution, researchers can train a single model to obtain both robust and efficient estimates for multiple target estimands at the same time, eliminating the need to fit separate semiparametric efficient estimators for each target. We assess this approach through simulations and an application estimating the age profile of retirement income.
title Ridge Boosting is Both Robust and Efficient
topic Methodology
url https://arxiv.org/abs/2510.22083