Refined Inference for Asymptotically Linear Estimators with Non-Negligible Second-Order Remainders

Fuente: arXiv
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Main Author: Li, Lin
Format: Preprint
Published: 2026
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author Li, Lin
author_facet Li, Lin
contents Asymptotically linear estimators in semiparametric models are usually studied through a von Mises expansion in which first-order inference is based on the influence-function variance. This reduction is valid only when the second-order remainder is negligible not only in probability but also in variance, a requirement not implied by the usual product-rate conditions ensuring asymptotic linearity. We study the regime in which the remainder contributes variance at order $n^{-1}$, so that the total sampling variance differs from the standard influence-function approximation by a non-vanishing first-order term. We derive a finite-sample variance decomposition separating the influence-function variance, the remainder variance, and their covariance, and characterize sandwich validity through the vanishing of scaled remainder variance: under a negligible cross term, the sandwich estimator is consistent for the total sampling variance when $n\,\mathrm{Var}(R_{\mathrm{rem}})\to 0$ and materially underestimates it in the complementary near-boundary regime $n\,\mathrm{Var}(R_{\mathrm{rem}})\to c_R>0$. We then establish asymptotic validity of two refined procedures in the near-boundary regime: the leave-one-out jackknife and the pairs bootstrap. Jackknife validity is obtained through a self-normalization argument; bootstrap validity is established directly under a Mallows--2 condition. We also extend the theory to clustered data and derive an analytic expression showing how intra-cluster correlation amplifies the sandwich gap through the remainder term. Simulations illustrate the regime and confirm the predicted coverage behaviour of the competing variance estimators.
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spellingShingle Refined Inference for Asymptotically Linear Estimators with Non-Negligible Second-Order Remainders
Li, Lin
Methodology
Statistics Theory
Asymptotically linear estimators in semiparametric models are usually studied through a von Mises expansion in which first-order inference is based on the influence-function variance. This reduction is valid only when the second-order remainder is negligible not only in probability but also in variance, a requirement not implied by the usual product-rate conditions ensuring asymptotic linearity. We study the regime in which the remainder contributes variance at order $n^{-1}$, so that the total sampling variance differs from the standard influence-function approximation by a non-vanishing first-order term. We derive a finite-sample variance decomposition separating the influence-function variance, the remainder variance, and their covariance, and characterize sandwich validity through the vanishing of scaled remainder variance: under a negligible cross term, the sandwich estimator is consistent for the total sampling variance when $n\,\mathrm{Var}(R_{\mathrm{rem}})\to 0$ and materially underestimates it in the complementary near-boundary regime $n\,\mathrm{Var}(R_{\mathrm{rem}})\to c_R>0$. We then establish asymptotic validity of two refined procedures in the near-boundary regime: the leave-one-out jackknife and the pairs bootstrap. Jackknife validity is obtained through a self-normalization argument; bootstrap validity is established directly under a Mallows--2 condition. We also extend the theory to clustered data and derive an analytic expression showing how intra-cluster correlation amplifies the sandwich gap through the remainder term. Simulations illustrate the regime and confirm the predicted coverage behaviour of the competing variance estimators.
title Refined Inference for Asymptotically Linear Estimators with Non-Negligible Second-Order Remainders
topic Methodology
Statistics Theory
url https://arxiv.org/abs/2603.16833