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Physical Sciences and Mathematics Commons

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Brigham Young University

Theses/Dissertations

Statistics and Probability

Mixed model

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Full-Text Articles in Physical Sciences and Mathematics

Separate And Joint Analysis Of Longitudinal And Survival Data, Deepthi Rajeev Mar 2007

Separate And Joint Analysis Of Longitudinal And Survival Data, Deepthi Rajeev

Theses and Dissertations

Chemotherapy is a method used to treat cancer but it has a number of side-effects. Research conducted by the Department of Chemical Engineering at BYU involves a new method of administering chemotherapy using ultrasound waves and water-soluble capsules. The goal is to reduce the side-effects by localizing the delivery of the medication. As part of this research, a two-factor experiment was conducted on rats to test if the water-soluble capsules and ultrasound waves by themselves have an effect on tumor growth or patient survival. Our project emphasizes the usage of Bayesian Hierarchical Models and Win-BUGS to jointly model the survival …


Selecting The Best Linear Mixed Model Using Predictive Approaches, Jun Wang Jan 2007

Selecting The Best Linear Mixed Model Using Predictive Approaches, Jun Wang

Theses and Dissertations

The linear mixed model is widely implemented in the analysis of longitudinal data. Inference techniques and information criteria are available and well-studied for goodness-of-fit within the linear mixed model setting. Predictive approaches such as R-squared, PRESS, and CCC are available for the linear mixed model but require more research (Edward, 2005). This project used simulation to investigate the performance of R-squared, PRESS, CCC, Pseudo F-test and information criterion for goodness-of-fit within the linear mixed model framework. Marginal and conditional approaches for these predictive statistics were studied under different variance-covariance structures. For compound symmetry structure, the success rates for all 17 …