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This paper proposes a Lasso-type estimator for a high-dimensional sparse parameter identified by a single index conditional moment restriction (CMR). In addition to this parameter, the moment function can also depend on a nuisance function,…

Statistics Theory · Mathematics 2021-09-14 Denis Nekipelov , Vira Semenova , Vasilis Syrgkanis

We show both adaptive and non-adaptive minimax rates of convergence for a family of weighted Laplacian-Eigenmap based nonparametric regression methods, when the true regression function belongs to a Sobolev space and the sampling density is…

Statistics Theory · Mathematics 2023-11-02 Zhaoyang Shi , Krishnakumar Balasubramanian , Wolfgang Polonik

We propose a new adaptive hypothesis test for inequality (e.g., monotonicity, convexity) and equality (e.g., parametric, semiparametric) restrictions on a structural function in a nonparametric instrumental variables (NPIV) model. Our test…

Econometrics · Economics 2024-11-08 Christoph Breunig , Xiaohong Chen

We develop new adaptive algorithms for variational inequalities with monotone operators, which capture many problems of interest, notably convex optimization and convex-concave saddle point problems. Our algorithms automatically adapt to…

Machine Learning · Computer Science 2021-08-30 Alina Ene , Huy L. Nguyen

This paper considers the problem of adaptive estimation of a template in a randomly shifted curve model. Using the Fourier transform of the data, we show that this problem can be transformed into a stochastic linear inverse problem. Our aim…

Statistics Theory · Mathematics 2009-11-10 Jérémie Bigot , Sébastien Gadat , Clément Marteau

We consider the problem of model selection type aggregation in the context of density estimation. We first show that empirical risk minimization is sub-optimal for this problem and it shares this property with the exponential weights…

Statistics Theory · Mathematics 2016-09-29 Pierre C. Bellec

In this paper for the first time the nonparametric autoregression estimation problem for the quadratic risks is considered. To this end we develop a new adaptive sequential model selection method based on the efficient sequential kernel…

Statistics Theory · Mathematics 2018-09-10 Ouerdia Arkoun , Jean-Yves Brua , Serguei Pergamenshchikov

We study optimal procedures for estimating a linear functional based on observational data. In many problems of this kind, a widely used assumption is strict overlap, i.e., uniform boundedness of the importance ratio, which measures how…

Statistics Theory · Mathematics 2023-01-18 Wenlong Mou , Peng Ding , Martin J. Wainwright , Peter L. Bartlett

We study the problem of learning Single-Index Models under the $L_2^2$ loss in the agnostic model. We give an efficient learning algorithm, achieving a constant factor approximation to the optimal loss, that succeeds under a range of…

Machine Learning · Computer Science 2024-02-28 Nikos Zarifis , Puqian Wang , Ilias Diakonikolas , Jelena Diakonikolas

Correctly identifying treatment effects in observational studies is very difficult due to the fact that the outcome model or the treatment assignment model must be correctly specified. Taking advantages of semiparametric models in this…

Methodology · Statistics 2022-07-08 Jichang Yu , Haibo Zhou , Jianwen Cai

We consider the problem of estimating the slope parameter in functional linear regression, where scalar responses Y1,...,Yn are modeled in dependence of second order stationary random functions X1,...,Xn. An orthogonal series estimator of…

Statistics Theory · Mathematics 2009-01-28 Jan Johannes

In sparse target inference problems it has been shown that significant gains can be achieved by adaptive sensing using convex criteria. We generalize previous work on adaptive sensing to (a) include multiple classes of targets with…

Information Theory · Computer Science 2014-09-30 Gregory E. Newstadt , Beipeng Mu , Dennis Wei , Jonathan P. How , Alfred O. Hero

We study clustered multitask learning in a semiparametric setting where tasks share a latent cluster structure in their target parameters but exhibit heterogeneous, potentially infinite-dimensional nuisance components. Such heterogeneity…

Machine Learning · Statistics 2026-05-05 Hanxiao Chen , Debarghya Mukherjee

We study the problem of nonparametric estimation of a multivariate function $g:\mathbb {R}^d\to\mathbb{R}$ that can be represented as a composition of two unknown smooth functions $f:\mathbb{R}\to\mathbb{R}$ and $G:\mathbb{R}^d\to…

Statistics Theory · Mathematics 2009-06-05 Anatoli B. Juditsky , Oleg V. Lepski , Alexandre B. Tsybakov

This paper explores adaptive variance reduction methods for stochastic optimization based on the STORM technique. Existing adaptive extensions of STORM rely on strong assumptions like bounded gradients and bounded function values, or suffer…

Optimization and Control · Mathematics 2024-10-24 Wei Jiang , Sifan Yang , Yibo Wang , Lijun Zhang

In this paper, we analyze the behavior of various non-parametric local regression estimators, i.e. estimators that are based on local averaging, for estimating a Lipschitz regression function at a fixed point, or in sup-norm. We first prove…

Statistics Theory · Mathematics 2025-07-11 Jérémy Bettinger , François Portier , Adrien Saumard

We consider the non-parametric Poisson regression problem where the integer valued response $Y$ is the realization of a Poisson random variable with parameter $\lambda(X)$. The aim is to estimate the functional parameter $\lambda$ from…

Statistics Theory · Mathematics 2018-05-14 Martin Kroll

Let $A:[0,1]\rightarrow\mathbb{H}_m$ (the space of Hermitian matrices) be a matrix valued function which is low rank with entries in H\"{o}lder class $\Sigma(\beta,L)$. The goal of this paper is to study statistical estimation of $A$ based…

Machine Learning · Statistics 2019-11-05 Fan Zhou

An adaptive regularization algorithm using inexact function and derivatives evaluations is proposed for the solution of composite nonsmooth nonconvex optimization. It is shown that this algorithm needs at most…

Optimization and Control · Mathematics 2019-02-28 S. Gratton , E. Simon , Ph. L. Toint

This paper deals with estimation with functional covariates. More precisely, we aim at estimating the regression function $m$ of a continuous outcome $Y$ against a standard Wiener coprocess $W$. Following Cadre and Truquet (2015) and Cadre,…

Statistics Theory · Mathematics 2020-11-23 Karine Bertin , Nicolas Klutchnikoff