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We tackle covariance estimation in low-sample scenarios, employing a structured covariance matrix with shrinkage methods. These involve convexly combining a low-bias/high-variance empirical estimate with a biased regularization estimator,…

Instrumentation and Methods for Astrophysics · Physics 2024-06-28 Olivier Flasseur , Eric Thiébaut , Loïc Denis , Maud Langlois

This paper studies the problem of interacting multiple model (IMM) estimation for jump Markov linear systems with unknown measurement noise covariance. The system state and the unknown covariance are jointly estimated in the framework of…

Systems and Control · Computer Science 2014-11-06 Wenling Li , Yingmin Jia

We introduce a novel class of Bayesian mixtures for normal linear regression models which incorporates a further Gaussian random component for the distribution of the predictor variables. The proposed cluster-weighted model aims to…

Methodology · Statistics 2026-05-26 Panagiotis Papastamoulis , Konstantinos Perrakis

In this paper, we show how to estimate the asymptotic (conditional) covariance matrix, which appears in central limit theorems in high-frequency estimation of asset return volatility. We provide a recipe for the estimation of this matrix by…

Econometrics · Economics 2026-01-26 Kim Christensen , Mark Podolskij , Nopporn Thamrongrat , Bezirgen Veliyev

Gaussian graphical models (GGMs) are well-established tools for probabilistic exploration of dependence structures using precision matrices. We develop a Bayesian method to incorporate covariate information in this GGMs setup in a nonlinear…

In this paper, we study robust covariance estimation under the approximate factor model with observed factors. We propose a novel framework to first estimate the initial joint covariance matrix of the observed data and the factors, and then…

Methodology · Statistics 2016-02-03 Jianqing Fan , Weichen Wang , Yiqiao Zhong

In independent component analysis it is assumed that the observed random variables are linear combinations of latent, mutually independent random variables called the independent components. Our model further assumes that only the…

Statistics Theory · Mathematics 2016-12-19 Joni Virta , Klaus Nordhausen , Hannu Oja

We investigate covariance shrinkage for Hotelling's $T^2$ in the regime where the data dimension $p$ and the sample size $n$ grow in a fixed ratio -- without assuming that the population covariance matrix is spiked or well-conditioned. When…

Statistics Theory · Mathematics 2025-06-13 Benjamin D. Robinson , Van Latimer

Tensor-valued data are being encountered increasingly more commonly, in the biological, natural as well as the social sciences. The learning of the unknown model parameter vector given such data, involves covariance modelling of such data,…

Applications · Statistics 2015-06-19 Kangrui Wang , Dalia Chakrabarty

We obtain the minimax rate for a mean location model with a bounded star-shaped set $K \subseteq \mathbb{R}^n$ constraint on the mean, in an adversarially corrupted data setting with Gaussian noise. We assume an unknown fraction $\epsilon…

Statistics Theory · Mathematics 2026-03-06 Akshay Prasadan , Matey Neykov

Spatial models are used in a variety research areas, such as environmental sciences, epidemiology, or physics. A common phenomenon in many spatial regression models is spatial confounding. This phenomenon takes place when spatially indexed…

Methodology · Statistics 2021-06-08 Isa Marques , Thomas Kneib , Nadja Klein

Gaussian graphical models (GGMs) are widely used to recover the conditional independence structure among random variables. Recent work has sought to incorporate auxiliary covariates to improve estimation, particularly in applications such…

Methodology · Statistics 2026-03-31 Ruobin Liu , Guo Yu

Let $M_n$ be a $n \times n$ Wigner or sample covariance random matrix, and let $\mu_1(M_n), \mu_2(M_n), ..., \mu_n(M_n)$ denote the unordered eigenvalues of $M_n$. We study the fluctuations of the partial linear eigenvalue statistics $$…

Probability · Mathematics 2015-08-06 Sean O'Rourke , Alexander Soshnikov

Bayesian approach to inverse problems is studied in the case where the forward map is a linear hypoelliptic pseudodifferential operator and measurement error is additive white Gaussian noise. The measurement model for an unknown Gaussian…

Statistics Theory · Mathematics 2016-07-20 Hanne Kekkonen , Matti Lassas , Samuli Siltanen

Cosine similarity is an established similarity metric for computing associations on vectors, and it is commonly used to identify related samples from biological perturbational data. The distribution of cosine similarity changes with the…

In this paper, state and noise covariance estimation problems for linear system with unknown multiplicative noise are considered. The measurement likelihood is modelled as a mixture of two Gaussian distributions and a Student's t…

Signal Processing · Electrical Eng. & Systems 2023-08-29 Xingkai Yu , Ziyang Meng

An accurate covariance matrix is essential for obtaining reliable cosmological results when using a Gaussian likelihood. In this paper we study the covariance of pseudo-$C_\ell$ estimates of tomographic cosmic shear power spectra. Using two…

In cryo-electron microscopy, the 3D electric potentials of an ensemble of molecules are projected along arbitrary viewing directions to yield noisy 2D images. The volume maps representing these potentials typically exhibit a great deal of…

Applications · Statistics 2018-02-08 Joakim Andén , Amit Singer

We consider the analysis of continuous repeated measurement outcomes that are collected through time, also known as longitudinal data. A standard framework for analysing data of this kind is a linear Gaussian mixed-effects model within…

Methodology · Statistics 2018-04-10 Özgür Asar , David Bolin , Peter J. Diggle , Jonas Wallin

This paper investigates the signal detection problem in colored Gaussian noise with an unknown covariance matrix. To be specific, we consider a sample deficient scenario in which the number of signal bearing samples ($n$) is strictly…

Signal Processing · Electrical Eng. & Systems 2024-04-26 Prathapasinghe Dharmawansa , Saman Atapattu , Jamie Evans , Kandeepan Sithamparanathan