Browsing Biostatistics by Title
Now showing items 72-91 of 104
-
On Estimation of Time-varying Population Attributable Fractions for Population-based Case-control Studies
The population attributable fraction (PAF) is an important measure in evaluating the contribution of risk factors to disease burden or mortality. It is a useful tool for planning of prevention actions. Recent development ... -
Parameter Selection of Sparse Functional Principal Component Analysis with fMRI data
With the advent of high throughput biotechnologies, it is increasingly common for the number of features measured on each subject to vastly exceed the number of subjects in modern biomedical studies. In this manuscript we ... -
Problems in Pedigrees and Phylogenies
(2013-07-23)The footprint of genetic inheritance can be observed among both familial relationships between individuals and evolutionary relationships between species. The former can be depicted by a pedigree, whereas the latter can ... -
Rare variant method for identity-by-descent detection in sequence data, and the time to most recent common ancestor given identity-by-descent segment length
(2013-11-14)Identity-by-descent (IBD) is defined as two individuals sharing a haplotype they have both inherited from a common ancestor, where a haplotype is a segment of genetic material found on a single homologue. Existing methods ... -
Recovering Natural History: Modeling Cardiovascular Biomarkers in the Presence of Endogenous Medication Use
In the modern era, cardiovascular biomarkers are often measured in the presence of medication use, whereby the observed value is different than the underlying untreated value for participants on medication. However, for ... -
Recurrent Episode Analyses of Pulmonary Exacerbations in the Infant Study of Inhaled Saline (ISIS) Trial
(2014-02-24)The Infant Study of Inhaled Saline (ISIS) randomized, controlled clinical trial evaluated the use of daily inhaled hypertonic saline treatment for 48 weeks to reduce the rate of pulmonary exacerbations in children of less ... -
Relationship of nighttime arousals and nocturnal cortisol in IBS and normal subjects
(2013-04-17)This study was a secondary analysis of data from a study investigating the association between inflammatory bowel syndrome (IBS) and nocturnal cortisol and catecholamines in a sample of IBS subjects and healthy controls. ... -
Risk Prediction In Cardiovascular Epidemiology: Considerations for Modeling Composite Endpoints
This thesis reviews construction and evaluation of risk prediction scores in the context of cardiovascular disease. We give an overview of the clinical guidelines that make use of cardiovascular disease risk scores as well ... -
Searching for Predictive Subgroups
Our increased understanding of genomics and related fields has led to: 1) the identification of subtypes of cancer based on various biomarkers and 2) the development of drugs to target specific subtypes. We then use clinical ... -
Semiparametric Analysis of an Expanded Cox Proportional Hazards Model with Time-Varying Covariates
Time-varying covariates are often encountered in survival analysis. The Cox proportional hazards model can incorporate time-varying covariates, while the interpretation of regression parameters is less straightforward. We ... -
A Sensitivity Analysis for Clinical Trials with Informatively Censored Survival Endpoints
(2013-02-25)Analyses of clinical trials with time-to-event endpoints typically employ the assumption of non-informative censoring. While this assumption is usually appropriate for end-of-study (EOS) censoring, its applicability to ... -
Sequential safety monitoring using observational data: A comparison of methods appropriate for newly-licensed vaccines in children
(2013-02-25)Sequential safety monitoring of newly-licensed vaccines is a national health priority and is routinely conducted using observational data. However, applying sequential methods in observational settings where the adverse ... -
Sieve Analysis: Statistical Methods for Assessing Genotype-Specific Vaccine Protection in HIV-1 Efficacy Trials with Multivariate and Missing Genotypes
(2012-09-13)The extensive diversity of the human immunodeficiency virus type 1 (HIV-1) poses a major challenge for the design of a successful preventive HIV-1 vaccine. Thus an important component of HIV-1 vaccine development is the ... -
Smoking and CVD in the Multi-Ethnic Study of Atherosclerosis: Functional Form, Mediating Pathways, and Implications of Intensity Reduction
Smoking as an epidemiological exposure can be quantified in terms of duration, intensity, pack-years, recency, and time of life. It is not clear which of these are important for cardiovascular disease, and how they should ... -
Spatial measurement error methods in air pollution epidemiology
Air pollution epidemiology cohort studies often implement a two-stage approach to estimating associations of continuous health outcomes with one or more exposures. An inherent problem in these studies is that the exposures ... -
Statistical inference for residual time quantiles in regression models for censored time-to-event data
(2014-02-24)In this dissertation, we set out to develop new methods for the analysis of time-to-event data. In particular, we are concerned with residual time, or the time remaining to an event after a certain amount of time has passed ... -
Statistical methods for analyzing genomic data with consideration of spatial structures
(2007)High-dimensional genetic data, such as DNA copy number and single nucleotide polymorphism (SNP), enable researchers unprecedented capabilities for studying genetic basis of diseases. In this dissertation, we develop ... -
Statistical Methods for Inferring Population Structure with Human Genome Sequence Data
Population structure is systematic variation in the human genome due to non-random mating because of physical or cultural barriers. Population structure is of interest in several fields of medicine, including population ... -
Statistical Methods for the Analysis of Autosomal and X Chromosome Genetic Data in Samples with Unknown Structure
Genome-wide association studies (GWAS) and sequencing association studies are routinely conducted for the mapping of genes to complex traits. Genetic variants on the X chromosome could potentially play an important role ... -
Statistical Methods in Admixture Mapping: Mixed Model Based Testing and Genome-wide Significance Thresholds
Genetic admixture occurs when two or more previously isolated populations combine to form an admixed population. The study of admixed populations can provide valuable insights into the complex relationship between environmental ...