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The paper proposes a new covariance estimator for large covariance matrices when the variables have a natural ordering. Using the Cholesky decomposition of the inverse, we impose a banded structure on the Cholesky factor, and select the…

Applications · Statistics 2008-12-18 Elizaveta Levina , Adam Rothman , Ji Zhu

We propose a flexible yet interpretable model for high-dimensional data with time-varying second order statistics, motivated and applied to functional neuroimaging data. Motivated by the neuroscience literature, we factorize the covariances…

Machine Learning · Statistics 2021-07-20 Katherine Tsai , Mladen Kolar , Oluwasanmi Koyejo

This article improves on existing methods to estimate the spectral density of stationary and nonstationary time series assuming a Gaussian process prior. By optimising an appropriate eigendecomposition using a smoothing spline covariance…

Methodology · Statistics 2022-06-01 Nick James , Max Menzies

We aim to develop simultaneous inference tools for the mean function of functional data from sparse to dense. First, we derive a unified Gaussian approximation to construct simultaneous confidence bands of mean functions based on the…

Methodology · Statistics 2024-02-01 Leheng Cai , Qirui Hu

In this paper we propose a computationally efficient algorithm for on-line variable selection in multivariate regression problems involving high dimensional data streams. The algorithm recursively extracts all the latent factors of a…

Machine Learning · Statistics 2009-02-10 Brian McWilliams , Giovanni Montana

Uni- and bivariate data smoothing with spline functions is a well established method in nonparametric regression analysis. The extension to multivariate data is straightforward, but suffers from exponentially increasing memory and…

Numerical Analysis · Mathematics 2024-12-20 Martin Siebenborn , Julian Wagner

We propose an l1-regularized likelihood method for estimating the inverse covariance matrix in the high-dimensional multivariate normal model in presence of missing data. Our method is based on the assumption that the data are missing at…

Methodology · Statistics 2012-02-28 Nicolas Städler , Peter Bühlmann

Sparse representation of structured signals requires modelling strategies that maintain specific signal properties, in addition to preserving original information content and achieving simpler signal representation. Therefore, the major…

Computer Vision and Pattern Recognition · Computer Science 2018-10-30 Branko Brkljač , Željen Trpovski

Gaussian processes (GP) are attractive building blocks for many probabilistic models. Their drawbacks, however, are the rapidly increasing inference time and memory requirement alongside increasing data. The problem can be alleviated with…

Machine Learning · Statistics 2012-03-19 Jarno Vanhatalo , Aki Vehtari

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

Estimating the covariance structure of multivariate time series is a fundamental problem with a wide-range of real-world applications -- from financial modeling to fMRI analysis. Despite significant recent advances, current state-of-the-art…

Machine Learning · Computer Science 2021-02-12 Hrayr Harutyunyan , Daniel Moyer , Hrant Khachatrian , Greg Ver Steeg , Aram Galstyan

The problem of estimating sparse eigenvectors of a symmetric matrix attracts a lot of attention in many applications, especially those with high dimensional data set. While classical eigenvectors can be obtained as the solution of a…

Machine Learning · Statistics 2016-11-03 Konstantinos Benidis , Ying Sun , Prabhu Babu , Daniel P. Palomar

Recent work has focused on the problem of conducting linear regression when the number of covariates is very large, potentially greater than the sample size. To facilitate this, one useful tool is to assume that the model can be well…

Methodology · Statistics 2011-11-21 Zhou Fang

We study the parameter estimation problem for a varying index coefficient model in high dimensions. Unlike the most existing works that iteratively estimate the parameters and link functions, based on the generalized Stein's identity, we…

Machine Learning · Statistics 2019-10-29 Sen Na , Zhuoran Yang , Zhaoran Wang , Mladen Kolar

This paper investigates the high-dimensional linear regression with highly correlated covariates. In this setup, the traditional sparsity assumption on the regression coefficients often fails to hold, and consequently many model selection…

Methodology · Statistics 2019-03-26 Jianqing Fan , Bai Jiang , Qiang Sun

This manuscript presents an approach to perform generalized linear regression with multiple high dimensional covariance matrices as the outcome. Model parameters are proposed to be estimated by maximizing a pseudo-likelihood. When the data…

Methodology · Statistics 2020-07-28 Yi Zhao , Brian S. Caffo , Xi Luo

Many scientific and economic applications involve the statistical learning of high-dimensional functional time series, where the number of functional variables is comparable to, or even greater than, the number of serially dependent…

Statistics Theory · Mathematics 2024-04-03 Jinyuan Chang , Cheng Chen , Xinghao Qiao , Qiwei Yao

Sparse covariates are frequent in classification and regression problems and in these settings the task of variable selection is usually of interest. As it is well known, sparse statistical models correspond to situations where there are…

Methodology · Statistics 2020-02-14 Ana M. Bianco , Graciela Boente , Gonzalo Chebi

Multivariate functional data from a complex system are naturally high-dimensional and have complex cross-correlation structure. The complexity of data structure can be observed as that (1) some functions are strongly correlated with similar…

Machine Learning · Statistics 2018-04-12 Chen Zhang , Hao Yan , Seungho Lee , Jianjun Shi

Functional data analysis finds widespread application across various fields. While functional data are intrinsically infinite-dimensional, in practice, they are observed only at a finite set of points, typically over a dense grid. As a…

Methodology · Statistics 2025-10-29 Ana Carolina da Cruz , Camila P. E. de Souza , Pedro H. T. O. Sousa
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