American Statistical Association
New York City
Metropolitan Area Chapter

Memorial Sloan-Kettering Cancer Center
Biostatistics Seminar



Adin-Cristian Andrei
Department of Biostatistics & Medical Informatics
University of Wisconsin-Madison

A NOVEL GAP TIME MODELING APPROACH
BASED ON PSEUDO-OBSERVATIONS

In numerous medical studies, participants may experiences a succession of landmark events. In cystic fibrosis, repeated pulmonary exacerbations episodes are an example of same-type events. In a cancer clinical trial, a sequence consisting of therapy initiation time, end of the toxicity period (TOX), end of the disease-free period (DF) and death represents a series of different-type events. Regardless of the event nature, the inter-event times are usually referred to as gap times. Conditional modeling of the gap times is often times challenging and practical implementation in mainstream statistical packages is not easily available. We propose a flexible, computationally efficient, novel modeling strategy based on jackknife pseudo-observations (POs). This construct requires an (approximately) unbiased nonparametric estimator for the joint distribution of the gap times. In essence, the problem is translated into the more accommodating realm of generalized linear models. Simulation studies show that the method proposed produces virtually unbiased covariate effect estimates, even for moderate sample sizes. An example from a medical study further illustrates the practical advantages of this new approach. Other time-to-event settings where this modeling strategy is extremely advantageous will also be discussed.


Date: Wednesday, May 12, 2010
Time: 4:00 - 5:00 P.M.
Location: Memorial Sloan-Kettering Cancer Center
Department of Epidemiology and Biostatistics
307 East 63rd Street
(between First and Second Avenues)
Room 331
New York, New York
Note: To gain access to the building, please follow the directions by the telephone in the foyer.

RESERVATIONS ARE NOT REQUIRED


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