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Covariate-adaptive randomization (CAR) procedures are frequently used in comparative studies to increase the covariate balance across treatment groups. However, because randomization inevitably uses the covariate information when forming…

Statistics Theory · Mathematics 2022-07-08 Wei Ma , Yichen Qin , Yang Li , Feifang Hu

This paper deals with the nonparametric density estimation of the regression error term assuming its independence with the covariate. The difference between the feasible estimator which uses the estimated residuals and the unfeasible one…

Statistics Theory · Mathematics 2010-10-05 Rawane Samb

Statistical inference on the explained variation of an outcome by a set of covariates is of particular interest in practice. When the covariates are of moderate to high-dimension and the effects are not sparse, several approaches have been…

Methodology · Statistics 2022-01-24 Hua Yun Chen

In this paper we study nonparametric estimators of copulas and copula densities. We first focus our study on a density copula estimator based on a polynomial orthogonal projection of the joint density. A new copula estimator is then…

Statistics Theory · Mathematics 2021-12-21 Yves Ismaël Ngounou Bakam , Denys Pommeret

Estimation of covariance matrices or their inverses plays a central role in many statistical methods. For these methods to work reliably, estimated matrices must not only be invertible but also well-conditioned. In this paper we present an…

Methodology · Statistics 2014-08-06 Eric C. Chi , Kenneth Lange

Shrinkage estimators of covariance are an important tool in modern applied and theoretical statistics. They play a key role in regularized estimation problems, such as ridge regression (aka Tykhonov regularization), regularized discriminant…

Statistics Theory · Mathematics 2011-05-10 Noureddine El Karoui , Holger Koesters

The statistical analysis of covariance matrix data is considered and, in particular, methodology is discussed which takes into account the non-Euclidean nature of the space of positive semi-definite symmetric matrices. The main motivation…

Applications · Statistics 2009-10-12 Ian L. Dryden , Alexey Koloydenko , Diwei Zhou

A new nonparametric estimator of a convex regression function in any dimension is proposed and its convergence properties are studied. We start by using any estimator of the regression function and we \emph{convexify} it by taking the…

Statistics Theory · Mathematics 2010-06-16 Néstor E. Aguilera , Liliana Forzani , Pedro Morin

A key challenge for robotic systems is to figure out the behavior of another agent. The capability to draw correct inferences is crucial to derive human behavior from examples. Processing correct inferences is especially challenging when…

Robotics · Computer Science 2022-07-19 Alexander Wich , Holger Schultheis , Michael Beetz

We propose a novel iterative algorithm for estimating a deterministic but unknown parameter vector in the presence of model uncertainties. This iterative algorithm is based on a system model where an overall noise term describes both, the…

Statistics Theory · Mathematics 2017-11-27 Oliver Lang , Michael Lunglmayr , Mario Huemer

We discuss symmetric quantum measurements and the associated covariant observables modelled, respectively, as instruments and positive-operator-valued measures. The emphasis of this work are the optimality properties of the measurements,…

Quantum Physics · Physics 2021-03-30 Erkka Haapasalo , Juha-Pekka Pellonpää

We study covariance matrix estimation for the case of partially observed random vectors, where different samples contain different subsets of vector coordinates. Each observation is the product of the variable of interest with a $0-1$…

Machine Learning · Statistics 2018-04-06 Eduardo Pavez , Antonio Ortega

The purpose of writing this book is to suggest some improved estimators using auxiliary information in sampling schemes like simple random sampling and systematic sampling. This volume is a collection of five papers. The following problems…

Statistics Theory · Mathematics 2013-08-28 Rajesh Singh , Florentin Smarandache

This paper proposes new estimators for the propensity score that aim to maximize the covariate distribution balance among different treatment groups. Heuristically, our proposed procedure attempts to estimate a propensity score model by…

Econometrics · Economics 2020-04-07 Pedro H. C. Sant'Anna , Xiaojun Song , Qi Xu

Estimation of a quadratic functional over parameter spaces that are not quadratically convex is considered. It is shown, in contrast to the theory for quadratically convex parameter spaces, that optimal quadratic rules are often rate…

Statistics Theory · Mathematics 2007-06-13 T. Tony Cai , Mark G. Low

Cointegration analysis was developed for non-stationary linear processes that exhibit stationary relationships between coordinates. Estimation of the cointegration relationships in a multi-dimensional cointegrated process typically proceeds…

Statistics Theory · Mathematics 2023-09-19 Christian Holberg , Susanne Ditlevsen

We derive a maximum a posteriori estimator for the linear observation model, where the signal and noise covariance matrices are both uncertain. The uncertainties are treated probabilistically by modeling the covariance matrices with prior…

Statistics Theory · Mathematics 2014-03-12 Dave Zachariah , Nafiseh Shariati , Mats Bengtsson , Magnus Jansson , Saikat Chatterjee

We investigate the nonparametric estimation for regression in a fixed-design setting when the errors are given by a field of dependent random variables. Sufficient conditions for kernel estimators to converge uniformly are obtained. These…

Statistics Theory · Mathematics 2007-06-13 Mohamed El Machkouri

Contour maps are widely used to display estimates of spatial fields. Instead of showing the estimated field, a contour map only shows a fixed number of contour lines for different levels. However, despite the ubiquitous use of these maps,…

Methodology · Statistics 2016-07-11 David Bolin , Finn Lindgren

We explore the information geometry and asymptotic behaviour of estimators for Kronecker-structured covariances, in both growing-$n$ and growing-$p$ scenarios, with a focus towards examining the quadratic form or partial trace estimator…

Statistics Theory · Mathematics 2023-08-07 Andrew McCormack , Peter Hoff