4:00 p.m. to 5:00 p.m. Austrian Auditorium, Clinical Research Building
Marcus Altfeld, MD, PhD Professor of Medicine Harvard Medical School The Ragon Institute of MGH, MIT and Harvard Co-Sponsored with the Immunology Graduate Group and HIV Grand Rounds
Professor of Medicine, HMS
Director, Innate Immunity Program
Ragon Institute of Massachusetts General Hospital, MIT and Harvard
"Innate immune responses in HIV infection"
Austrian Auditorium, CRB
Abstract: Outcome-dependent sampling can be found in many follow-up studies where data are collected according to a cross-sectional sampling scheme under certain eligibility criteria. A motivating example is the Biomarkers for Older Controls at Risk for Dementia (BIOCARD) Study, which enrolled cognitively normal individuals from a wide age range at baseline and followed the participants until failure or censoring. Such a sampling scheme tends to oversample individuals with longer survival time, because individuals who have already failed at the time of recruitment will not be included. The covariates correlated with survival time are also subject to sampling bias, which, if ignored, could lead to biased inferences. This talk considers estimation of the prediction/classification accuracy of baseline biomarkers when data are collected under outcome-dependent sampling. We derive a bias correction function for the distribution function of the baseline biomarkers and propose semiparametric bias-corrected estimators for Receiver Operating Characteristic (ROC) curves and Positive Predictive Value (PPV) curves under proportional hazards assumption. The proposed estimators are consistent and converge to Gaussian processes, while substantial biases may arise if standard estimators ignoring left truncation are used. The proposed approach is further illustrated using data from the BIOCARD study.
Penn Biomedical Policy Group Meeting - Tue, Jan 15th at 6pm in BRB 251.
Interested in discussing the issue of scientific funding? The Penn Biomedical Policy Group will host a discussion on this topic, including how looming budget cuts will affect funding, at their next meeting, on Tuesday Jan 15th. Shaun O'Brien, Ellen Elliot, and Mike Allegrezza will intro the topic with a brief background and then moderate the discussion. If you can't make it, but are interested in learning about science policy and exploring career options, please email Mike Allegrezza ( firstname.lastname@example.org ) to be added to the group's listserv. -- From the computer of Shaun O'Brien
Note earlier time- Takeshi Tanigawa, MD, PhD,Professor & Chairman, Department of Public Health, Ehime University, Japan
“Screening for Sleep Disordered Breathing in Communities and Workplaces in Japan”