Sökning: "Dependency Theory"

Visar resultat 16 - 20 av 108 avhandlingar innehållade orden Dependency Theory.

  1. 16. Contributions to Estimation and Testing Block Covariance Structures in Multivariate Normal Models

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

    Sammanfattning : 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. LÄS MER

  3. 17. Methods for longitudinal brain imaging studies with dropout

    Författare :Tetiana Gorbach; Xavier de Luna; Anders Lundquist; Martin A. Lindquist; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Missing data; nonignorable dropout; sensitivity analysis; uncertainty intervals; pattern-mixture models; aging; cognition; MRI; brain structure; resting-state functional connectivity; Statistics; statistik;

    Sammanfattning : One of the challenges in aging research is to understand the brain mechanisms that underlie cognitive development in older adults. Such aging processes are investigated in longitudinal studies, where the within-individual changes over time are observed. However, several methodological issues exist in longitudinal analyses. LÄS MER

  4. 18. Resampling in network modeling of high-dimensional genomic data

    Författare :Jonatan Kallus; Göteborgs universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; high-dimensional data; sparsity; model selection; bootstrap; genomics; graphical modeling;

    Sammanfattning : Network modeling is an effective approach for the interpretation of high-dimensional data sets for which a sparse dependence structure can be assumed. Genomic data is a challenging and important example. In genomics, network modeling aids the discovery of biological mechanistic relationships and therapeutic targets. LÄS MER

  5. 19. On flexible random field models for spatial statistics: Spatial mixture models and deformed SPDE models

    Författare :Anders Hildeman; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Spatial statistics; Significant wave height; Spatial mixture model; Stochastic partial differential equation; Log-Gaussian Cox process; Point process; Gaussian random field; Substitute-CT;

    Sammanfattning : Spatial random fields are one of the key concepts in statistical analysis of spatial data. The random field explains the spatial dependency and serves the purpose of regularizing interpolation of measured values or to act as an explanatory model. LÄS MER

  7. 20. Spatial Mixture Models with Applications in Medical Imaging and Spatial Point Processes

    Författare :Anders Hildeman; Göteborgs universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Non-Gaussian; Bayesian level set inversion; Point processes; Substitute CT; Finite mixture models; Spatial statistics; Gaussian fields; Non-Gaussian;

    Sammanfattning : Finite mixture models have proven to be a great tool for both modeling non-standard probability distributions and for classification problems (using the latent variable interpretation). In this thesis we are building spatial models by incorporating spatially dependent categorical latent random fields in a hierarchical manner similar to that of finite mixture models. LÄS MER