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In this paper, we highlight a major error in the proofs of the important results of [D.Ch\'etelat and M. T. Wells(2012). Improved Multivariate Normal Mean Estimation with Unknown Covariance when p is Greater than n. The Annals of…

Statistics Theory · Mathematics 2024-06-25 Arash A. Foroushani , Severien Nkurunziza

We consider the problem of estimating covariance and precision matrices, and their associated discriminant coefficients, from normal data when the rank of the covariance matrix is strictly smaller than its dimension and the available sample…

Statistics Theory · Mathematics 2015-09-09 Didier Chételat , Martin T. Wells

We consider the problem of estimating the mean vector of a p-variate normal $(\theta,\Sigma)$ distribution under invariant quadratic loss, $(\delta-\theta)'\Sigma^{-1}(\delta-\theta)$, when the covariance is unknown. We propose a new class…

Statistics Theory · Mathematics 2013-02-28 Didier Chételat , Martin T. Wells

Estimation of the mean vector and covariance matrix is of central importance in the analysis of multivariate data. In the framework of generalized linear models, usually the variances are certain functions of the means with the normal…

Methodology · Statistics 2023-01-25 Anupam Kundu , Mohsen Pourahmadi

Estimation of the covariance matrix has attracted a lot of attention of the statistical research community over the years, partially due to important applications such as Principal Component Analysis. However, frequently used empirical…

Statistics Theory · Mathematics 2018-06-19 Stanislav Minsker

Stein's paradox holds considerable sway in high-dimensional statistics, highlighting that the sample mean, traditionally considered the de facto estimator, might not be the most efficacious in higher dimensions. To address this, the…

Computer Vision and Pattern Recognition · Computer Science 2023-12-04 Seyedalireza Khoshsirat , Chandra Kambhamettu

The family of rank estimators, including Han's maximum rank correlation (Han, 1987) as a notable example, has been widely exploited in studying regression problems. For these estimators, although the linear index is introduced for…

Statistics Theory · Mathematics 2019-08-15 Yanqin Fan , Fang Han , Wei Li , Xiao-Hua Zhou

When inferring parameters from a Gaussian-distributed data set by computing a likelihood, a covariance matrix is needed that describes the data errors and their correlations. If the covariance matrix is not known a priori, it may be…

Cosmology and Nongalactic Astrophysics · Physics 2016-01-27 Elena Sellentin , Alan F. Heavens

We study a linear high-dimensional regression model in a semi-supervised setting, where for many observations only the vector of covariates $X$ is given with no response $Y$. We do not make any sparsity assumptions on the vector of…

Statistics Theory · Mathematics 2021-09-03 Ilan Livne , David Azriel , Yair Goldberg

The covariance matrix plays a fundamental role in many modern exploratory and inferential statistical procedures, including dimensionality reduction, hypothesis testing, and regression. In low-dimensional regimes, where the number of…

Methodology · Statistics 2024-11-12 Philippe Boileau , Nima S. Hejazi , Mark J. van der Laan , Sandrine Dudoit

In this paper, we consider the problem of parameter estimating for a family of exponential distributions. We develop the improved estimation method, which generalized the James--Stein approach for a wide class of distributions. The proposed…

Statistics Theory · Mathematics 2023-08-08 S. B. Kologrivova , E. A. Pchelintsev

Relying on recent advances in statistical estimation of covariance distances based on random matrix theory, this article proposes an improved covariance and precision matrix estimation for a wide family of metrics. The method is shown to…

Machine Learning · Statistics 2021-02-03 Malik Tiomoko , Florent Bouchard , Guillaume Ginholac , Romain Couillet

We present an estimator of the covariance matrix $\Sigma$ of random $d$-dimensional vector from an i.i.d. sample of size $n$. Our sole assumption is that this vector satisfies a bounded $L^p-L^2$ moment assumption over its one-dimensional…

Statistics Theory · Mathematics 2024-03-27 Roberto I. Oliveira , Zoraida F. Rico

This paper develops a bias correction scheme for a multivariate normal model under a general parameterization. In the model, the mean vector and the covariance matrix share the same parameters. It includes many important regression models…

Methodology · Statistics 2009-05-06 Alexandre G. Patriota , Artur J. Lemonte

This paper provides a framework for estimating the mean and variance of a high-dimensional normal density. The main setting considered is a fixed number of vector following a high-dimensional normal distribution with unknown mean and…

Methodology · Statistics 2019-05-07 Shyamalendu Sinha , Jeffrey D. Hart

In the realm of high-dimensional data analysis, the estimation of covariance matrices is a fundamental task, and this holds true for interval-valued data as well. However, there is no unified definition for the covariance matrix of…

Methodology · Statistics 2026-04-02 Wan Tian , Wenhao Cui , Rui Zhang , Bingyi Jing , Yang Liu , Yijie Peng

Identification of multinomial choice models is often established by using special covariates that have full support. This paper shows how these identification results can be extended to a large class of multinomial choice models when all…

Econometrics · Economics 2022-03-23 Nail Kashaev

The problem of reducing the bias of maximum likelihood estimator in a general multivariate elliptical regression model is considered. The model is very flexible and allows the mean vector and the dispersion matrix to have parameters in…

Statistics Theory · Mathematics 2016-02-01 Tatiane F. N. Melo , Silvia L. P. Ferrari , Alexandre G. Patriota

Estimating the unconstrained mean and covariance matrix is a popular topic in statistics. However, estimation of the parameters of $N_p(\mu,\Sigma)$ under joint constraints such as $\Sigma\mu = \mu$ has not received much attention. It can…

Methodology · Statistics 2023-01-25 Anupam Kundu , Mohsen Pourahmadi

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
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