Prokhorov Metric Convergence of the Partial Sum Process for Reconstructed Functional Data

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Autori principali: Kutta, Tim, Kokoszka, Piotr
Natura: Preprint
Pubblicazione: 2025
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author Kutta, Tim
Kokoszka, Piotr
author_facet Kutta, Tim
Kokoszka, Piotr
contents Motivated by applications in functional data analysis, we study the partial sum process of sparsely observed, random functions. A key novelty of our analysis are bounds for the distributional distance between the limit Brownian motion and the entire partial sum process in the function space. To measure the distance between distributions, we employ the Prokhorov and Wasserstein metrics. We show that these bounds have important probabilistic implications, including strong invariance principles and new couplings between the partial sums and their Gaussian limits. Our results are formulated for weakly dependent, nonstationary time series in the Banach space of d-dimensional, continuous functions. Mathematically, our approach rests on a new, two-step proof strategy: First, using entropy bounds from empirical process theory, we replace the function-valued partial sum process by a high-dimensional discretization. Second, using Gaussian approximations for weakly dependent, high-dimensional vectors, we obtain bounds on the distance. As a statistical application of our coupling results, we validate an open-ended monitoring scheme for sparse functional data. Existing probabilistic tools were not appropriate for this task.
format Preprint
id arxiv_https___arxiv_org_abs_2506_21172
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Prokhorov Metric Convergence of the Partial Sum Process for Reconstructed Functional Data
Kutta, Tim
Kokoszka, Piotr
Statistics Theory
62M10, 62R10
Motivated by applications in functional data analysis, we study the partial sum process of sparsely observed, random functions. A key novelty of our analysis are bounds for the distributional distance between the limit Brownian motion and the entire partial sum process in the function space. To measure the distance between distributions, we employ the Prokhorov and Wasserstein metrics. We show that these bounds have important probabilistic implications, including strong invariance principles and new couplings between the partial sums and their Gaussian limits. Our results are formulated for weakly dependent, nonstationary time series in the Banach space of d-dimensional, continuous functions. Mathematically, our approach rests on a new, two-step proof strategy: First, using entropy bounds from empirical process theory, we replace the function-valued partial sum process by a high-dimensional discretization. Second, using Gaussian approximations for weakly dependent, high-dimensional vectors, we obtain bounds on the distance. As a statistical application of our coupling results, we validate an open-ended monitoring scheme for sparse functional data. Existing probabilistic tools were not appropriate for this task.
title Prokhorov Metric Convergence of the Partial Sum Process for Reconstructed Functional Data
topic Statistics Theory
62M10, 62R10
url https://arxiv.org/abs/2506.21172