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Activity Number:
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526
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Type:
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Invited
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Date/Time:
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Thursday, August 10, 2006 : 10:30 AM to 12:20 PM
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Sponsor:
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Biopharmaceutical Section
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| Abstract - #305077 |
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Title:
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Adjusted Nelson-Aalen Estimator with Inverse Probability of Treatment Weighting
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Author(s):
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Jun Xie*+ and Chaofeng Liu
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Companies:
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Purdue University and Eli Lilly and Company
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Address:
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Department of Statistics, West Lafayette, IN, 47907,
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Keywords:
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adjusted Nelson-Aalen estimator ; hazards rate ; inverse probability of treatment weighting ; weighted log-rank test
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Abstract:
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Estimation and group comparison of survival rates are two very common issues in survival analysis. In nonrandomized clinical trials or observational studies, the Nelson-Aalen estimator of hazards rate function may be biased due to unbalanced distributions of confounding variables. We develop an Adjusted Nelson-Aalen Estimator (ANAE) with Inverse Probability of Treatment Weighting (IPTW). Each observation is weighted by its inverse probability of being in a certain group. The ANAE estimates marginal hazards rate function without the assumption of proportionality. It is a consistent estimate. A weighted log-rank test is developed for comparing group difference of hazards rates. Simulation and real data studies illustrate the ANAE and weighted log-rank test outperform the Nelson-Aalen estimate, and it does better than or as well as other estimators based on stratification.
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