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Abstract Details
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Activity Number:
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266
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Type:
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Invited
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Date/Time:
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Tuesday, July 31, 2012 : 8:30 AM to 10:20 AM
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Sponsor:
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International Indian Statistical Association
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| Abstract - #303674 |
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Title:
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Efficiency: A Moving Target for Adaptive Designs
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Author(s):
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Cyrus R Mehta*+
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Companies:
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Cytel Inc.
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Address:
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675 Massachusetts Avenue, Cambridge, MA, 02139,
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Keywords:
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Sample Size Re-estimation ;
Clinical Trials ;
Group Sequential
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Abstract:
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The use of observed treatment effects to re-estimate the sample size of a randomized clinical trial has gradually gained regulatory acceptance and is adopted fairly frequently in industry trials. Nevertheless, the idea is still somewhat controversial, especially among academic statisticians who express concerns about loss of efficiency, unreliability of interim estimates and reduced interpretablity of the results. We show that these concerns are highly exaggerated in realistic settings where the advantages of sample size re-estimation are transparent and efficiency loss is negligible. An influential paper by Tsiatis and Mehta (Biometrika, 2003) showing the greater efficiency of the classical group sequential approach over the adaptive approach is re-visited with fresh insights about the definition of efficiency gained from many years of consulting on industry trials.
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Authors who are presenting talks have a * after their name.
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