Sökning: "pattern- mixture models"

Visar resultat 1 - 5 av 14 avhandlingar innehållade orden pattern- mixture models.

  1. 1. Attrition in Studies of Cognitive Aging

    Författare :Maria Josefsson; Xavier de Luna; Lars Nyberg; Anders Lundquist; Mattias Villani; Umeå universitet; []
    Nyckelord :SAMHÄLLSVETENSKAP; SOCIAL SCIENCES; Attrition; missing data; age-related cognitive change; non- ignorable dropout; monotone missing pattern; mixture models; pattern- mixture models; imputation; Statistics; statistik;

    Sammanfattning : Longitudinal studies of cognition are preferred to cross-sectional stud- ies, since they offer a direct assessment of age-related cognitive change (within-person change). Statistical methods for analyzing age-related change are widely available. LÄS MER

  3. 2. 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

  4. 3. Differences and similarities in work absence behavior : - empirical evidence from micro data

    Författare :Maria Nilsson; Mårten Palme; Jan Erik Askildsen; Växjö universitet; []
    Nyckelord :SAMHÄLLSVETENSKAP; SOCIAL SCIENCES; moral hazard; gender difference; immigrants; panel data; count data models; fixed effects; finite mixture models; Economics; Nationalekonomi; Economics; Nationalekonomi;

    Sammanfattning : This thesis consists of three self-contained essays about absenteeism. Essay I analyzes if the design of the insurance system affects work absence, i.e. the classic insurance problem of moral hazard. LÄS MER

  5. 4. 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

  7. 5. Statistical Segmentation and Registration of Medical Ultrasound Data

    Författare :Mattias Hansson; Matematik LTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Registration; Segmentation; Feature descriptor; Statistical image and signal processing; Medical ultrasound; Variational methods; Mixture model; Bayesian; Markov Chain Monte Carlo; Similarity measur;

    Sammanfattning : The interpretation of ultrasonic imagery is typically not straightforward and of quite subjective nature and therefore strongly dependent on the expertise of its users. Thus the development of algorithms which aid in the interpretation of ultrasonic data is a highly relevant topic. LÄS MER