Uncertainty quantification for iterative algorithms in linear models with application to early stopping
- URL: http://arxiv.org/abs/2404.17856v1
- Date: Sat, 27 Apr 2024 10:20:41 GMT
- Title: Uncertainty quantification for iterative algorithms in linear models with application to early stopping
- Authors: Pierre C. Bellec, Kai Tan,
- Abstract summary: This paper investigates the iterates $hbb1,dots,hbbT$ obtained from iterative algorithms in high-dimensional linear regression problems.
The analysis and proposed estimators are applicable to Gradient Descent (GD), GD and their accelerated variants such as Fast Iterative Soft-Thresholding (FISTA)
- Score: 4.150180443030652
- License: http://creativecommons.org/licenses/by/4.0/
- Abstract: This paper investigates the iterates $\hbb^1,\dots,\hbb^T$ obtained from iterative algorithms in high-dimensional linear regression problems, in the regime where the feature dimension $p$ is comparable with the sample size $n$, i.e., $p \asymp n$. The analysis and proposed estimators are applicable to Gradient Descent (GD), proximal GD and their accelerated variants such as Fast Iterative Soft-Thresholding (FISTA). The paper proposes novel estimators for the generalization error of the iterate $\hbb^t$ for any fixed iteration $t$ along the trajectory. These estimators are proved to be $\sqrt n$-consistent under Gaussian designs. Applications to early-stopping are provided: when the generalization error of the iterates is a U-shape function of the iteration $t$, the estimates allow to select from the data an iteration $\hat t$ that achieves the smallest generalization error along the trajectory. Additionally, we provide a technique for developing debiasing corrections and valid confidence intervals for the components of the true coefficient vector from the iterate $\hbb^t$ at any finite iteration $t$. Extensive simulations on synthetic data illustrate the theoretical results.
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