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Bibliographic Details
Main Authors: Derumigny, Alexis, Schmidt-Hieber, Johannes
Format: Preprint
Published: 2023
Subjects:
Online Access:https://arxiv.org/abs/2303.11706
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Table of Contents:
  • In nonparametric statistics, rate-optimal estimators typically balance bias and stochastic error. The recent work on overparametrization raises the question whether rate-optimal estimators exist that do not obey this trade-off. In this work we consider pointwise estimation in the Gaussian white noise model with regression function $f$ in a class of $β$-Hölder smooth functions. Let 'worst-case' refer to the supremum over all functions $f$ in the Hölder class. It is shown that any estimator with worst-case bias $\lesssim n^{-β/(2β+1)}=: ψ_n$ must necessarily also have a worst-case mean absolute deviation that is lower bounded by $\gtrsim ψ_n.$ To derive the result, we establish abstract inequalities relating the change of expectation for two probability measures to the mean absolute deviation.