Document Type

Dissertation - University Access Only

Award Date

2012

Degree Name

Doctor of Philosophy (PhD)

Department / School

Mathematics and Statistics

First Advisor

Gemechis Dilba Djira

Abstract

In longitudinal studies measurements are repeatedly taken on the same individual over time. So, in these studies observations from the same individual are correlated to each other. The main purpose in longitudinal studies is to analyze changes in the response variable over time in relation to other covariates such as treatment group, baseline characteristics, and so forth. This dissertation research has four chapters that are focused on four different topics in longitudinal studies. In the first chapter, we proposed a technique to compare the several linear profiles simultaneously in the context of longitudinal data. In the second chapter, we investigated the influence of different mineral intake (Study 1), timing of the introduction of solid foods (Study 2), and gross motor activity (Study 3) on bone accrual during the first year of life using liner mixed effects models. In the third chapter, we considered the same three studies that were investigated in chapter 2 and proposed a Bayesian hierarchical model to combine longitudinal studies. In the fourth chapter, we considered various models for modeling dose-time-response data. Our objective was to build various time dependent dose-response models, and compare non-longitudinal and longitudinal dose-time-response models in terms of their efficiency.

Library of Congress Subject Headings

Longitudinal method
Infants -- Development -- Longitudinal studies
Bones -- Growth -- Longitudinal studies
Dose-response relationship (Biochemistry)

Publisher

South Dakota State University

Download

Share

COinS
 

Rights Statement

In Copyright