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The correlated Wishart model provides the standard benchmark when analyzing time series of any kind. Unfortunately, the real case, which is the most relevant one in applications, poses serious challenges for analytical calculations. Often…

Mathematical Physics · Physics 2018-08-08 Tim Wirtz , Mario Kieburg , Thomas Guhr

Gaussian covariance graph models encode marginal independence among the components of a multivariate random vector by means of a graph $G$. These models are distinctly different from the traditional concentration graph models (often also…

Statistics Theory · Mathematics 2011-03-10 Kshitij Khare , Bala Rajaratnam

This paper deals with the asymptotic distribution of Wishart matrix and its application to the estimation of the population matrix parameter when the population eigenvalues are block-wise infinitely dispersed. We show that the appropriately…

Statistics Theory · Mathematics 2008-04-06 Yo Sheena , Akimichi Takemura

In this paper, we want to show the Restricted Wishart distribution is equivalent to the LKJ distribution, which is one way to specify a uniform distribution from the space of positive definite correlation matrices. Based on this theorem, we…

Computation · Statistics 2018-09-14 Zhenxun Wang , Yunan Wu , Haitao Chu

We study a new family of random variables, that each arise as the distribution of the maximum or minimum of a random number $N$ of i.i.d.~random variables $X_1,X_2,\ldots,X_N$, each distributed as a variable $X$ with support on $[0,1]$. The…

Statistics Theory · Mathematics 2014-03-07 Jie Hao , Anant Godbole

We study parameter estimation in linear Gaussian covariance models, which are $p$-dimensional Gaussian models with linear constraints on the covariance matrix. Maximum likelihood estimation for this class of models leads to a non-convex…

Statistics Theory · Mathematics 2016-04-19 Piotr Zwiernik , Caroline Uhler , Donald Richards

Wishart random matrix theory is of major importance for the analysis of correlated time series. The distribution of the smallest eigenvalue for Wishart correlation matrices is particularly interesting in many applications. In the complex…

Mathematical Physics · Physics 2013-10-21 Tim Wirtz , Thomas Guhr

In the last decade, there has been a growing interest to use Wishart processes for modelling, especially for financial applications. However, there are still few studies on the estimation of its parameters. Here, we study the Maximum…

Statistics Theory · Mathematics 2016-04-18 Aurélien Alfonsi , Ahmed Kebaier , Clément Rey

We give an approximate formula for the distribution of the largest eigenvalue of real Wishart matrices by the expected Euler characteristic method for the general dimension. The formula is expressed in terms of a definite integral with…

Statistics Theory · Mathematics 2020-05-25 Nobuki Takayama , Lin Jiu , Satoshi Kuriki , Yi Zhang

In this paper, we give an explicitdescription of a class of positive measures on symmetric conesdefined by their Laplace transforms in the framework of the Rieszintegrals. This work is motivated by the importance of thesemeasures in…

Probability · Mathematics 2017-05-12 Abdelhamid Hassairi , Sallouha Lajmi

We derive concentration inequalities for the spectral measure of large random matrices, allowing for certain forms of dependence. Our main focus is on empirical covariance (Wishart) matrices, but general symmetric random matrices are also…

Statistics Theory · Mathematics 2018-09-24 Adityanand Guntuboyina , Hannes Leeb

In this paper the maximum likelihood equations for the parameters of the Weight Lindley distribution are studied considering different types of censoring, such as, type I, type II and random censoring mechanism. A numerical simulation study…

Methodology · Statistics 2015-03-31 Pedro L. Ramos , Francisco Louzada , Vicente G. Cancho

We obtain the complete conjugacy invariants of expansive Lorenz maps and for any given two expansive Lorenz maps, there are two unique sequences of $(\beta_{i},\alpha_{i})$ pairs. In this way, we can define the classification of expansive…

Dynamical Systems · Mathematics 2021-04-01 Yiming Ding , Yun Sun

This paper considers the maximum likelihood estimation of factor models of high dimension, where the number of variables (N) is comparable with or even greater than the number of observations (T). An inferential theory is developed. We…

Statistics Theory · Mathematics 2012-05-31 Jushan Bai , Kunpeng Li

This paper studies two-stage distributionally robust conic linear programming under constraint uncertainty over type-1 Wasserstein balls. We present optimality conditions for the dual of the worst-case expectation problem, which…

Optimization and Control · Mathematics 2024-02-06 Geunyeong Byeon , Kaiwen Fang , Kibaek Kim

Birnbaum-Saunders models have been widely used to model positively skewed data. In this paper, we introduce a bivariate Birnbaum-Saunders distribution which has the means as parameters. We present some properties of the univariate and…

Methodology · Statistics 2018-05-01 Helton Saulo , Jeremias Leão , Roberto Vila , Victor Leiva , Vera Tomazella

This paper proposes a unified approach that enables the Wishart distribution to be studied simultaneously in the real, complex, quaternion and octonion cases. In particular, the noncentral generalised Wishart distribution, the joint density…

Statistics Theory · Mathematics 2010-10-12 Jose A. Diaz-Garcia , Ramon Gutierrez-Jaimez

Mechanistic network models specify the mechanisms by which networks grow and change, allowing researchers to investigate complex systems using both simulation and analytical techniques. Unfortunately, it is difficult to write likelihoods…

Methodology · Statistics 2023-07-19 Jonathan Larson , Jukka-Pekka Onnela

In this paper, we propose a new distribution with unitary support which can be characterized as a ratio of the type $W=X_1/(X_1+X_2)$, where $(X_1, X_2)^\top$ follows a bivariate extreme distribution with Fr\'echet margins, that is, $X_1$…

Methodology · Statistics 2025-01-03 Roberto Vila , Felipe Quintino

These lecture notes provide a comprehensive, self-contained introduction to the analysis of Wishart matrix moments. This study may act as an introduction to some particular aspects of random matrix theory, or as a self-contained exposition…

Probability · Mathematics 2019-02-12 Adrian N. Bishop , Pierre Del Moral , Angele Niclas