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Finding an unconstrained and statistically interpretable reparameterization of a covariance matrix is still an open problem in statistics. Its solution is of central importance in covariance estimation, particularly in the recent…

Methodology · Statistics 2012-02-09 Mohsen Pourahmadi

We consider the problem of estimating high-dimensional covariance matrices of $K$-populations or classes in the setting where the sample sizes are comparable to the data dimension. We propose estimating each class covariance matrix as a…

Methodology · Statistics 2022-02-08 Elias Raninen , David E. Tyler , Esa Ollila

Statistical models that possess symmetry arise in diverse settings such as random fields associated to geophysical phenomena, exchangeable processes in Bayesian statistics, and cyclostationary processes in engineering. We formalize the…

Statistics Theory · Mathematics 2011-12-01 Parikshit Shah , Venkat Chandrasekaran

The Riemannian geometry of covariance matrices has been essential to several successful applications, in computer vision, biomedical signal and image processing, and radar data processing. For these applications, an important ongoing…

Statistics Theory · Mathematics 2017-05-15 Salem Said , Hatem Hajri , Lionel Bombrun , Baba C. Vemuri

Gaussian variational approximation is a popular methodology to approximate posterior distributions in Bayesian inference especially in high dimensional and large data settings. To control the computational cost while being able to capture…

Machine Learning · Computer Science 2021-04-07 Bingxin Zhou , Junbin Gao , Minh-Ngoc Tran , Richard Gerlach

Joint network topology inference represents a canonical problem of jointly learning multiple graph Laplacian matrices from heterogeneous graph signals. In such a problem, a widely employed assumption is that of a simple common component…

Statistics Theory · Mathematics 2021-07-09 Yanli Yuan , De Wen Soh , Xiao Yang , Kun Guo , Tony Q. S. Quek

This paper considers a high-dimensional linear regression problem where there are complex correlation structures among predictors. We propose a graph-constrained regularization procedure, named Sparse Laplacian Shrinkage with the Graphical…

Methodology · Statistics 2019-04-10 Yuehan Yang , Siwei Xia , Hu Yang

This work introduces a novel approach for generating conditional probabilistic rainfall forecasts with temporal and spatial dependence. A two-step procedure is employed. Firstly, marginal location-specific distributions are jointly…

Methodology · Statistics 2025-03-31 David Huk , Rilwan A. Adewoyin , Ritabrata Dutta

Generalized additive models (GAMs) provide a way to blend parametric and non-parametric (function approximation) techniques together, making them flexible tools suitable for many modeling problems. For instance, GAMs can be used to…

Methodology · Statistics 2023-03-07 Antti Solonen , Stratos Staboulis

Diffusion models can generate a variety of high-quality images by modeling complex data distributions. Trained diffusion models can also be very effective image priors for solving inverse problems. Most of the existing diffusion-based…

Image and Video Processing · Electrical Eng. & Systems 2025-09-01 Nebiyou Yismaw , Ulugbek S. Kamilov , M. Salman Asif

We study the problem of estimating from data, a sparse approximation to the inverse covariance matrix. Estimating a sparsity constrained inverse covariance matrix is a key component in Gaussian graphical model learning, but one that is…

Machine Learning · Statistics 2011-06-28 Suvrit Sra , Dongmin Kim

We consider the problem of minimizing a block separable convex function (possibly nondifferentiable, and including constraints) plus Laplacian regularization, a problem that arises in applications including model fitting, regularizing…

Optimization and Control · Mathematics 2018-04-02 Jonathan Tuck , David Hallac , Stephen Boyd

We consider a distributed estimation method in a setting with heterogeneous streams of correlated data distributed across nodes in a network. In the considered approach, linear models are estimated locally (i.e., with only local data)…

Machine Learning · Computer Science 2021-02-11 Lingzhou Hong , Alfredo Garcia , Ceyhun Eksin

Estimating covariance parameters for multivariate spatial Gaussian random fields is computationally challenging, as the number of parameters grows rapidly with the number of variables, and likelihood evaluation requires operations of order…

Methodology · Statistics 2026-04-10 Francisco Cuevas-Pacheco , Gabriel Riffo , Xavier Emery

Using a hierarchical construction, we develop methods for a wide and flexible class of models by taking a fully parametric approach to generalized linear mixed models with complex covariance dependence. The Laplace approximation is used to…

Methodology · Statistics 2024-07-31 Jay M. Ver Hoef , Eryn Blagg , Michael Dumelle , Philip M. Dixon , Dale L. Zimmerman , Paul Conn

Regularization is a common tool in variational inverse problems to impose assumptions on the parameters of the problem. One such assumption is sparsity, which is commonly promoted using lasso and total variation-like regularization.…

Statistics Theory · Mathematics 2023-02-15 Jasper Marijn Everink , Yiqiu Dong , Martin Skovgaard Andersen

In this paper, the problem of state estimation, in the context of both filtering and smoothing, for nonlinear state-space models is considered. Due to the nonlinear nature of the models, the state estimation problem is generally intractable…

Machine Learning · Statistics 2021-11-24 Jarrad Courts , Adrian Wills , Thomas B. Schön

Laplacian mixture models identify overlapping regions of influence in unlabeled graph and network data in a scalable and computationally efficient way, yielding useful low-dimensional representations. By combining Laplacian eigenspace and…

Machine Learning · Statistics 2018-10-03 Daniel Korenblum

We consider covariance estimation in the multivariate generalized Gaussian distribution (MGGD) and elliptically symmetric (ES) distribution. The maximum likelihood optimization associated with this problem is non-convex, yet it has been…

Methodology · Statistics 2015-06-15 Teng Zhang , Ami Wiesel , Maria Sabrina Grec

We consider the problem of finding tuned regularized parameter estimators for linear models. We start by showing that three known optimal linear estimators belong to a wider class of estimators that can be formulated as a solution to a…

Statistics Theory · Mathematics 2023-05-03 Per Mattsson , Dave Zachariah , Petre Stoica