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Browsing Dissertations and Theses by Subject "biostatistics"
Now showing items 1-20 of 79
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A computational pipeline for identifying copy number variation from single nucleotide polymorphism data and applications to congenital heart disease
Copy number variants (CNVs) are duplications or deletions of regions of the genome. CNVs, similar to single nucleotide variants (SNVs), range in frequency and severity in their effects on human disease. Despite the likely ... -
A method for quantifying the regression to the mean effect applied to bivariate binary outcomes in the presence of limited baseline data
In studies lacking a control group, a crucial step in estimating the study effect is to tease apart the proportion of the total observed change in key outcomes which are due to study participation, from that which is caused ... -
A Simpler Model for the Impact of Atrial Fibrillation on Cognitive Trajectories in the Elderly
In their 2013 paper “Atrial fibrillation and cognitive decline: A longitudinal cohort study”, Dr. Thacker and colleagues investigated whether, in the absence of clinical stroke, incident atrial fibrillation was associated ... -
Adaptive designs in the time to event setting: The potential for benefit and risk
Group sequential designs (GSDs) have been the standard sequential approach to maintain scientific, ethical, and efficiency goals in any confirmatory Phase III studies. Over the past two decades, adaptive extensions to group ... -
Adaptive Randomization Ratios in Multi-arm Clinical Trials
Ethics and economics are two of many motivations for streamlining the process of discovering new therapies for the treatment of human disease. Population ethics and economics dictate that any true benefit be demonstrated ... -
Addressing Lagged Effects and Interval Censoring in the Stepped Wedge Design of Cluster Randomized Clinical Trials
(2014-02-24)The stepped wedge design (SWD) of cluster-randomized trials has been growing in popularity and is increasingly being used to efficiently evaluate the rollout of interventions in a community setting. The design is especially ... -
Adjusting for Misclassified Outcomes in a Multistate Model
(2013-07-25)In this dissertation, we present a new model that accounts for time-dependent sensitivity in multivariate outcome survival models. Our problem was motivated by an interest in estimating baseline risk and associated covariates ... -
An Evaluation of Flexible Summary Measures for the Comparison of Binary Outcomes in Non-Inferiority Trials
In clinical trials, the comparison of binary outcomes between two independent treatment groups is most commonly measured by either relative or absolute differences between outcome rates. In the setting of a non-inferiority ... -
Analysis of biased sampling designs using longitudinal data
With increasing availability of prospective cohort studies, registry data, and electronic health records, numerous secondary investigations are being conducted using data that were originally collected for a different ... -
Assessing measurement error correction for genotype imputation in GWAS
(2013-04-17)Abstract not available -
Assessing Vaccine Effects in HIV-1 Vaccine Trials: Antigenic Maps, Antigen Selection, and Sieve Analysis
(2014-02-24)The goal of vaccination against infectious disease is a net population effect on the risk of infection and/or disease progression. In HIV-1 vaccine development efforts to date only a single HIV-1 vaccine trial has shown ... -
Assessing Vaccine Effects on Infectiousness in COVID-19 Vaccine Trials
Vaccines have played an important role in the public health response to the COVID-19 pandemic. Clinical trials for several candidate vaccines demonstrated high efficacy at pre- venting severe / symptomatic disease. These ... -
The Bayesian Analysis of Data Arising from Complex Sampling Designs
(2013-04-17)The majority of this thesis concerns the development of Bayesian methods for two-phase studies. A two-phase study is a study design in which limited information (including outcome) is known for a large "first-phase" study ... -
Bayesian estimation of participants’ adherence in an HIV prevention trial using multiple data sources and pharmacokinetic models
Pre-Exposure Prophylaxis (PrEP) is an HIV prevention practice which uses antiretrovial drugs to keep HIV-negative individuals from infection with HIV. One of the antiretrovi ral drugs that is usually used for HIV treatment ... -
Biostatistical Methods for HIV Monitoring and Prevention
Part I Pooled-testing methods can greatly reduce the number of tests needed to identify failures in a collection of samples. Existing methodology has focused primarily on binary tests, but there is a clear need for improved ... -
Causal Inference with Selection and Confounding Variables
Most complex observational and randomized studies are motivated by the potential of drawing causal statements. However, a usual statistical analysis may yield estimates that do not have causal interpretations. In fact, ... -
Causal mediation analysis with failure time outcome and error-prone longitudinal covariate
Mediation analyses are important for understanding the biological mechanisms whereby a treatment/exposure influences an outcome of interest. For example, one may be interested in whether body fat accumulation mediates an ... -
Challenges Associated with Statistical Analysis in the Presence of Sparse Data and Applications to Alternative Tobacco Product Research
(2013-07-23)Rarely observed covariate combinations, or "sparsity" is a phenomenon associated with research concerning the health risks of alternative-use (non-combusted tobacco products (AUPs)). Of particular concern is sparsity ... -
A Comparison of Sample Size Calculations for Cluster Randomized Crossover Trials with a Binary Outcome
A simplified sample size calculation for a cluster randomized crossover trial with a binary survival outcome (the “ T-BOSS ” method) was compared to the closed form equation and simulation methods currently available from ... -
Covariate Measurement Error Correction Methods in Mediation Analysis with Failure Time Data
(2013-04-17)Mediation analysis is important in understanding the mechanisms of one variable causing changes in another. Measurement error could be obscuring the ability of the potential mediator to explain this mechanism. Existing ...