Browsing Biostatistics by Title
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Adaptive Randomization Ratios in Multiarm 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 ... 
Additive hazards regression with incomplete covariate data
(1997)This dissertation addresses two incomplete covariate data problems in the additive hazards (AH) regression model for failure time data. Both are examples of twophase designs where some covariate is measured only on a ... 
Addressing Lagged Effects and Interval Censoring in the Stepped Wedge Design of Cluster Randomized Clinical Trials
(20140224)The stepped wedge design (SWD) of clusterrandomized 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
(20130725)In this dissertation, we present a new model that accounts for timedependent 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 NonInferiority 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 noninferiority ... 
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 ... 
Analysis of binary longitudinal data with dropout and death
(2002)Dropout (attrition) is a common challenge in analysis of longitudinal data. Additionally, data records may be truncated due to the death of study participants. Response data missing due to death are often modeled by the ... 
Aspects of matching and power in group randomized trials
(2001)A group randomized trial is an experiment in which groups, such as communities, schools or workplaces, are randomized to receive treatment or act as controls. Frequently, the number of groups is small. Because it is the ... 
Assessing accuracy of a continuous medical diagnostic or screening test in the presence of verification bias
(2000)In studies to assess accuracy of a medical diagnostic or screening test, often definitive disease assessment is too invasive or expensive to be ascertained in all subjects. It makes practical and ethical sense to select a ... 
Assessing measurement error correction for genotype imputation in GWAS
(20130417)Abstract not available 
Assessing the Accuracy of Provider Profiling Methods for Classification
(20120913)Provider profiling as a means to describe and compare performance of health care professionals has gained great momentum in the past decade. The implications of profiling, which can drive provider incentives and guide ... 
Assessing Vaccine Effects in HIV1 Vaccine Trials: Antigenic Maps, Antigen Selection, and Sieve Analysis
(20140224)The goal of vaccination against infectious disease is a net population effect on the risk of infection and/or disease progression. In HIV1 vaccine development efforts to date only a single HIV1 vaccine trial has shown ... 
The Bayesian Analysis of Data Arising from Complex Sampling Designs
(20130417)The majority of this thesis concerns the development of Bayesian methods for twophase studies. A twophase study is a study design in which limited information (including outcome) is known for a large "firstphase" study ... 
Bayesian estimation of participants’ adherence in an HIV prevention trial using multiple data sources and pharmacokinetic models
PreExposure Prophylaxis (PrEP) is an HIV prevention practice which uses antiretrovial drugs to keep HIVnegative individuals from infection with HIV. One of the antiretrovi ral drugs that is usually used for HIV treatment ... 
Bayesian Hierarchical Frailty Models for Heterogeneity in Risk
The effect of an intervention or exposure on timetoevent is most commonly estimated with the Cox model, which assumes proportional hazards. When heterogeneity in risk is present, the assumption of proportionality is ... 
Biostatistical Methods for HIV Monitoring and Prevention
Part I Pooledtesting 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 in HIV vaccine trials: comparing outcomes in a subset chosen after randomization
(2005)In many experiments researchers would like to compare between treatments an outcome that only exists in a subset of participants selected after randomization. For example, in preventative HIV vaccine efficacy trials it is ... 
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 errorprone 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
(20130723)Rarely observed covariate combinations, or "sparsity" is a phenomenon associated with research concerning the health risks of alternativeuse (noncombusted tobacco products (AUPs)). Of particular concern is sparsity ...