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Covariance matrix estimation is an important problem in multivariate data analysis, both from theoretical as well as applied points of view. Many simple and popular covariance matrix estimators are known to be severely affected by model…

Methodology · Statistics 2025-11-21 Soumya Chakraborty , Ayanendranath Basu , Abhik Ghosh

We study sample covariance matrices arising from multi-level components of variance. Thus, let $ B_n=\frac{1}{N}\sum_{j=1}^NT_{j}^{1/2}x_jx_j^TT_{j}^{1/2}$, where $x_j\in R^n$ are i.i.d. standard Gaussian, and…

Probability · Mathematics 2024-06-07 Ran Xie , Iain Johnstone

In this work we consider the estimation of spatio-temporal covariance matrices in the low sample non-Gaussian regime. We impose covariance structure in the form of a sum of Kronecker products decomposition (Tsiligkaridis et al. 2013,…

Methodology · Statistics 2014-05-14 Kristjan Greenewald , Alfred O. Hero

Linear discriminant analysis (LDA) is a typical method for classification problems with large dimensions and small samples. There are various types of LDA methods that are based on the different types of estimators for the covariance…

Methodology · Statistics 2023-03-07 Jaehoan Kim , Hoyoung Park , Junyong Park

Linear discriminant analysis (LDA) based classifiers tend to falter in many practical settings where the training data size is smaller than, or comparable to, the number of features. As a remedy, different regularized LDA (RLDA) methods…

Machine Learning · Computer Science 2021-03-30 Alam Zaib , Tarig Ballal , Shahid Khattak , Tareq Y. Al-Naffouri

In this paper, we present an algorithm for learning time-correlated measurement covariances for application in batch state estimation. We parameterize the inverse measurement covariance matrix to be block-banded, which conveniently…

Robotics · Computer Science 2023-03-14 David J. Yoon , Timothy D. Barfoot

This paper addresses the problem of estimating the Hermitian Toeplitz covariance matrix under practical hardware constraints of sparse observations and coarse quantization. Within the triangular-dithered quantization framework, we propose…

Signal Processing · Electrical Eng. & Systems 2025-12-30 Hongwei Xu , Weichao Zheng , Zai Yang

Covariance estimation for matrix-valued data has received an increasing interest in applications. Unlike previous works that rely heavily on matrix normal distribution assumption and the requirement of fixed matrix size, we propose a class…

Methodology · Statistics 2022-04-20 Yichi Zhang , Weining Shen , Dehan Kong

In semivarying coefficient models for longitudinal/clustered data, usually of primary interest is usually the parametric component which involves unknown constant coefficients. First, we study semiparametric efficiency bound for estimation…

Methodology · Statistics 2015-09-15 Ming-Yen Cheng , Toshio Honda , Jialiang Li

We consider estimation of covariance matrices and their inverses (a.k.a. precision matrices) for high-dimensional stationary and locally stationary time series. In the latter case the covariance matrices evolve smoothly in time, thus…

Statistics Theory · Mathematics 2014-01-07 Xiaohui Chen , Mengyu Xu , Wei Biao Wu

This paper investigates regularized estimation of Kronecker-structured covariance matrices (CM) for polarization radar in sea clutter scenarios where the data are assumed to follow the complex, elliptically symmetric (CES) distributions…

Signal Processing · Electrical Eng. & Systems 2022-02-08 Lei Xie , Zishu He , Jun Tong , Tianle Liu , Jun Li , Jiangtao Xi

The main theme of this paper is a modification of the likelihood ratio test (LRT) for testing high dimensional covariance matrix. Recently, the correct asymptotic distribution of the LRT for a large-dimensional case (the case $p/n$…

Methodology · Statistics 2019-04-16 Young-Geun Choi , Chi Tim Ng , Johan Lim

The problem of noise covariance matrix identification of stochastic linear time-varying state-space models is addressed. The measurement difference method (MDM) is generalized to time-varying dimensions of the measurement and control. Three…

Signal Processing · Electrical Eng. & Systems 2024-12-11 Oliver Kost , Jindrch Dunik , Ondrej Straka

Multivariate time series present many challenges, especially when they are high dimensional. The paper's focus is twofold. First, we address the subject of consistently estimating the autocovariance sequence; this is a sequence of matrices…

Statistics Theory · Mathematics 2015-06-03 Carsten Jentsch , Dimitris N. Politis

We present a comparison between various algorithms of inference of covariance and precision matrices in small datasets of real vectors, of the typical length and dimension of human brain activity time series retrieved by functional Magnetic…

Statistical Mechanics · Physics 2023-02-07 Miguel Ibáñez-Berganza , Carlo Lucibello , Francesca Santucci , Tommaso Gili , Andrea Gabrielli

The subspace-based techniques are widely utilized in various scientific fields, and they need accurate estimation of the signal subspace dimension. The classic RMT estimator for model order estimation based on random matrix theory assumes…

Information Theory · Computer Science 2025-05-06 Huiyue Yi , Wuxiong Zhang , Hui Xu

Let $\mathbf{X}_n=(x_{ij})$ be a $k \times n$ data matrix with complex-valued, independent and standardized entries satisfying a Lindeberg-type moment condition. We consider simultaneously $R$ sample covariance matrices…

Statistics Theory · Mathematics 2018-01-23 Weiming Li , Zeng Li , Jianfeng Yao

In this paper, we study the strong consistency of a bias reduced kernel density estimator and derive a strongly con- sistent Kullback-Leibler divergence (KLD) estimator. As application, we formulate a goodness-of-fit test and an…

Methodology · Statistics 2018-05-21 Papa Ngom , Freedath Djibril Moussa , Jean de Dieu Nkurunziza

Spectral estimators are fundamental in lowrank matrix models and arise throughout machine learning and statistics, with applications including network analysis, matrix completion and PCA. These estimators aim to recover the leading…

Statistics Theory · Mathematics 2025-02-17 Hao Yan , Keith Levin

Representational similarity analysis (RSA) tests models of brain computation by investigating how neural activity patterns reflect experimental conditions. Instead of predicting activity patterns directly, the models predict the geometry of…