Modeling and Analyzing Multivariate Longitudinal Left-censored Biomarker Data

The first part of this dissertation addresses the analysis of multiple biomarkers subject to left-censoring over time. Imputation methods and methods that account for censoring are extended to handle multiple outcomes and are compared and evaluated for both accuracy and efficiency through a simulation study. Estimation is based on a parametric multivariate linear mixed model for longitudinally measured biomarkers. For left censored biomarkers an extension of this method based on MLE is used.