This thesis consists of three papers which investigate marginal models, nonparametric approaches, generalized mixed effects models and variance components estimation in longitudinal data analysis. In the first paper, a new marginal approach is introduced for high-dimensional cell-cycle microarray data with no replicates. There are two kinds of correlation for cell-cycle...
We propose a new classification method for longitudinal data based on a semiparametric approach. Our approach builds a classifier by taking advantage of modeling information between response and covariates for each class, and assigns a new subject to the class with the smallest quadratic distance. This enables one to overcome...
The words we use to define our lives are often determined by the way we render any given moment. Every instance of writing is a moment of remembering, and a non-fiction essay gives the author free rein to unravel an instance, paint a portrait of what time has already come...
Missing data can lead to biased and inefficient estimation if the missing mechanism is not taken into account in the analysis. In this dissertation we propose two estimators that, under fairly general conditions, are asymptotically unbiased. The first proposed estimator assume the data are missing at random (MAR) and does...
This dissertation seeks to contribute to a growing body of research on student outcomes by way of a public health perspective examining the intersection of education policy and adolescent mental health and well-being. The conceptual approach underpinning this project rests on the key theoretical assumption that education policy, shaped at...
Pancreatic beta cells produce and release insulin, a vital hormone that regulates blood glucose levels, and their dysfunction contributes to the development of diabetes mellitus. Dietary zinc deficiency and exposure to the toxicant inorganic arsenic have both independently been associated with diabetes, although the effects of their combination on pancreatic...
Research Objective: Nearly 60 million people in the United States reside in a rural area. Residents in rural areas have higher rates of chronic disease, risky health behaviors, disability, infant mortality, and age-adjusted mortality than their urban counterparts. Health insurance and access to care mitigate those risks, in part because...
In cross-cultural studies, respondents from specific cultures may have different product preferences and scale usage. Combining data from different cultures will result in departures from the basic assumptions of analysis of variance (ANOVA) and loss of power in testing capability of finding product and culture differences. However, the result of...
Fowl sperm are believed to be immotile prior to ejaculation. The concentration of
potassium found in deferent duct fluid is approximately 8 times higher than that found
in blood plasma, which is 5 mM in Gallus domesticus. The effect of ionic potassium
on fowl sperm motion was tested in a...
The purpose of this study was to determine the relative tolerance of grafted
Vitis rootstocks to low soil pH. In this capacity, the data may be pooled with results
from previous investigations to increase the overall aptitude profile of Vitis
rootstocks. A potential application of this information is that the...