Search for dissertations about: "Covariance structures"

Showing result 1 - 5 of 21 swedish dissertations containing the words Covariance structures.

2. 1. A study of multilevel models with block circular  symmetric covariance structures

   Author : Yuli Liang; Tatjana von Rosen; Dietrich von Rosen; Abdullah Almasri; Stockholms universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Block circular symmetry; Covariance matrix; Explicit solution; Maximum likelihood estimator; Multilevel model; Spectrum; statistik; Statistics; Matematik;

   Abstract : This thesis concerns the study of multilevel models with specific patterned covariance structures and addresses the issues of maximum likelihoodestimation. In particular, circular symmetric hierarchical datastructures are considered. READ MORE

4. 2. Contributions to Estimation and Testing Block Covariance Structures in Multivariate Normal Models

   Author : Yuli Liang; Tatjana von Rosen; Dietrich von Rosen; Ivan Žežula; Stockholms universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Block circular symmetry; covariance parameters; explicit maximum likelihood estimator; likelihood ratio test; restricted model; Toeplitz matrix; Statistics; statistik;

   Abstract : This thesis concerns inference problems in balanced random effects models with a so-called block circular Toeplitz covariance structure. This class of covariance structures describes the dependency of some specific multivariate two-level data when both compound symmetry and circular symmetry appear simultaneously. READ MORE

5. 3. Statistical modeling and design in forestry : The case of single tree models

   Author : Leakemariam Berhe; Göran Arnoldsson; Göran Broström; Dieter Rasch; Umeå universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Forest data; Covariance structures; Nonlinear mixed effects models; Tree taper models; Ds-optimal design; Replication-free design.; Statistics; Statistik;

   Abstract : Forest quantification methods have evolved from a simple graphical approach to complex regression models with stochastic structural components. Currently, mixed effects models methodology is receiving attention in the forestry literature. READ MORE

6. 4. Bilinear and Trilinear Regression Models with Structured Covariance Matrices

   Author : Joseph Nzabanita; Dietrich von Rosen; Martin Singull; Miguel Fonseca; Linköpings universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES;

   Abstract : This thesis focuses on the problem of estimating parameters in bilinear and trilinear regression models in which random errors are normally distributed. In these models the covariance matrix has a Kronecker product structure and some factor matrices may be linearly structured. READ MORE

7. 5. Estimation in Multivariate Linear Models with Linearly Structured Covariance Matrices

   Author : Joseph Nzabanita; Dietrich von Rosen; Martin Singull; Daniel Klein; Linköpings universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES;

   Abstract : This thesis focuses on the problem of estimating parameters in multivariate linear models where particularly the mean has a bilinear structure and the covariance matrix has a linear structure. Most of techniques in statistical modeling rely on the assumption that data were generated from the normal distribution. READ MORE