Penalized Spline M-Estimators for Discretely Sampled Functional Data: Existence and Asymptotics

Fuente: arXiv
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Main Author: Kalogridis, Ioannis
Format: Preprint
Published: 2025
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author Kalogridis, Ioannis
author_facet Kalogridis, Ioannis
contents Location estimation is a central problem in functional data analysis. In this paper, we investigate penalized spline estimators of location for discretely sampled functional data under a broad class of convex loss functions. Our framework generalizes and extends previously derived results for non-robust estimators to a broad penalized M-estimation framework. The analysis is built on two general-purpose non-asymptotic theoretical tools: (i) a non-asymptotic existence result for penalized spline estimators under minimal design conditions, and (ii) a localization lemma that captures both stochastic variability and approximation error. Under mild assumptions, we establish optimal convergence rates and identify the small- and large-knot regimes, along with the critical breakpoint known from penalized spline theory in nonparametric regression. Our results imply that parametric rates are attainable even with discretely sampled data and numerical experiments demonstrate that our estimators match or exceed the robustness of competing estimators while being considerably more computationally attractive.
format Preprint
id arxiv_https___arxiv_org_abs_2508_12000
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Penalized Spline M-Estimators for Discretely Sampled Functional Data: Existence and Asymptotics
Kalogridis, Ioannis
Methodology
Location estimation is a central problem in functional data analysis. In this paper, we investigate penalized spline estimators of location for discretely sampled functional data under a broad class of convex loss functions. Our framework generalizes and extends previously derived results for non-robust estimators to a broad penalized M-estimation framework. The analysis is built on two general-purpose non-asymptotic theoretical tools: (i) a non-asymptotic existence result for penalized spline estimators under minimal design conditions, and (ii) a localization lemma that captures both stochastic variability and approximation error. Under mild assumptions, we establish optimal convergence rates and identify the small- and large-knot regimes, along with the critical breakpoint known from penalized spline theory in nonparametric regression. Our results imply that parametric rates are attainable even with discretely sampled data and numerical experiments demonstrate that our estimators match or exceed the robustness of competing estimators while being considerably more computationally attractive.
title Penalized Spline M-Estimators for Discretely Sampled Functional Data: Existence and Asymptotics
topic Methodology
url https://arxiv.org/abs/2508.12000