"Analysis of Longitudinal Data Under Biased Sampling"
Yong Chen, Ph.D. Assistant Professor Division of Biostatistics University of Texas School of Public Health Abstract:Over the past few decades, a dramatic increase in the incidence of obesity has become a worldwide health issue, contributing significantly as a risk factor of many diseases. Many individuals participate in web-based weight loss programs where their weights, physical activities and diets are self-reported. Such web-based program generated data poses new challenges to statistical modeling and inference, including subject-specific self-reporting times and outcome-dependent missingness. These challenges are known as biased sampling problem in statistical literature, and can lead to substantial bias in inference. In this talk, we propose a framework of novel statistical methods to efficiently detect and adjust for sampling bias, and to evaluate both the overall effectiveness of the weight loss program and the subject-specific effects of website usages on weight loss. The proposed methods provide elegant solutions for detecting and eliminating the impacts of biased sampling, and can achieve unbiased inference without fully specifying the complex data-generating mechanism. We apply the proposed methods to evaluate the effectiveness of a web-based program on weight loss, controlling the nonlinear trajectory of weights over time.
"Understanding the Impact of Neighborhoods on Health: Evidence and Challenges "
Ana V. Diez Roux, MD, PhD, MPH
Dean of the School of Public Health at Drexel University
"Pediatric Leukemia: Endeavors to Establish Evidence-Based Approaches for Supportive Care”
Brian T. Fisher, DO, MSCE, MPH
Assistant Professor of Pediatrics
Division of Infectious Diseases
“The TiME Trial: A Model for Pragmatic Clinical Trials in Dialysis"
Professor of Medicine, Renal-Electrolyte and Hypertension Division
Perelman School of Medicine, University of Pennsylvania
“ Clinical Epidemiology Studies in Pediatric Leukemia”
Richard Aplenc, MD, PhD, MSCE
Associate Professor of Pediatrics,
CHOP, University of Pennsylvania
“Case Fatality and Population Mortality Associated with Anaphylaxis in the United States”
Larry MA, PhD
Johnson & Johnson Consumer Products Company
"Issues and challenges to analyze Genome-wide Methylation data and possible solutions.”
Hemant K. Tiwari PhD William "Student" Sealy Gosset Professor Head, Section on Statistical Genetics Department of Biostatistics University of Alabama at Birmingham School of Public Health
Abstract: For complex diseases there often exists the problem of missing heritability. It is continually debated whether this is because of highly complex genetic architecture that is not accounted for, or if there are actually greater heritable contributions unrelated to the actual DNA sequence itself in the study of epigenetics. An epigenetic modification is defined as any alteration to DNA that does not affect the sequence itself but serves a function and is retained when the cell divides. The study of epigenetics may provide vital information that can be used to provide a better understanding of this phenotypic variability among individuals. The most widely studied and perhaps the foundational epigenetic modification is DNA methylation. However, there are challenges to DNA methylation data analysis, specifically the analysis of DNA from the Illumina Methyl450 array which is a relatively new area that presents both computational and statistical challenges. This talk will cover issues with quality control, genome-wide heritability estimation, and association methods for DNA methylation as well provide possible solutions.