Generalized van Trees inequality: Local minimax bounds for non-smooth functionals and irregular statistical models

Fuente: arXiv
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Main Authors: Takatsu, Kenta, Kuchibhotla, Arun Kumar
Format: Preprint
Published: 2024
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author Takatsu, Kenta
Kuchibhotla, Arun Kumar
author_facet Takatsu, Kenta
Kuchibhotla, Arun Kumar
contents In a decision-theoretic framework, the minimax lower bound provides the worst-case performance of estimators relative to a given class of statistical models. For parametric and semiparametric models, the Hájek--Le Cam local asymptotic minimax (LAM) theorem provides the sharp local asymptotic lower bound. Despite its relative generality, this result comes with limitations as it only applies to the estimation of differentiable functionals under regular statistical models. On the other hand, minimax lower bound techniques such as Fano's or Assoud's are applicable in more general settings but are not sharp enough to imply the LAM theorem. To address this gap, we provide new non-asymptotic minimax lower bounds under minimal regularity assumptions, which imply sharp asymptotic constants. The proposed lower bounds do not require the differentiability of functionals or regularity of statistical models, extending the efficiency theory to broader situations where standard results fail. The use of the new lower bounds is illustrated through the local minimax lower bound constants for estimating the density at a point and directionally differentiable parameters.
format Preprint
id arxiv_https___arxiv_org_abs_2405_06437
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Generalized van Trees inequality: Local minimax bounds for non-smooth functionals and irregular statistical models
Takatsu, Kenta
Kuchibhotla, Arun Kumar
Statistics Theory
In a decision-theoretic framework, the minimax lower bound provides the worst-case performance of estimators relative to a given class of statistical models. For parametric and semiparametric models, the Hájek--Le Cam local asymptotic minimax (LAM) theorem provides the sharp local asymptotic lower bound. Despite its relative generality, this result comes with limitations as it only applies to the estimation of differentiable functionals under regular statistical models. On the other hand, minimax lower bound techniques such as Fano's or Assoud's are applicable in more general settings but are not sharp enough to imply the LAM theorem. To address this gap, we provide new non-asymptotic minimax lower bounds under minimal regularity assumptions, which imply sharp asymptotic constants. The proposed lower bounds do not require the differentiability of functionals or regularity of statistical models, extending the efficiency theory to broader situations where standard results fail. The use of the new lower bounds is illustrated through the local minimax lower bound constants for estimating the density at a point and directionally differentiable parameters.
title Generalized van Trees inequality: Local minimax bounds for non-smooth functionals and irregular statistical models
topic Statistics Theory
url https://arxiv.org/abs/2405.06437