Document Detail


Optimal conditional error functions for the control of conditional power.
MedLine Citation:
PMID:  15339294     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Ethical considerations and the competitive environment of clinical trials usually require that any given trial have sufficient power to detect a treatment advance. If at an interim analysis the available data are used to decide whether the trial is promising enough to be continued, investigators and sponsors often wish to have a high conditional power, which is the probability to reject the null hypothesis given the interim data and the alternative of interest. Under this requirement a design with interim sample size recalculation, which keeps the overall and conditional power at a prespecified value and preserves the overall type I error rate, is a reasonable alternative to a classical group sequential design, in which the conditional power is often too small. In this article two-stage designs with control of overall and conditional power are constructed that minimize the expected sample size, either for a simple point alternative or for a random mixture of alternatives given by a prior density for the efficacy parameter. The presented optimality result applies to trials with and without an interim hypothesis test; in addition, one can account for constraints such as a minimal sample size for the second stage. The optimal designs will be illustrated with an example, and will be compared to the frequently considered method of using the conditional type I error level of a group sequential design.
Authors:
Werner Brannath; Peter Bauer
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Biometrics     Volume:  60     ISSN:  0006-341X     ISO Abbreviation:  Biometrics     Publication Date:  2004 Sep 
Date Detail:
Created Date:  2004-09-01     Completed Date:  2005-03-01     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  0370625     Medline TA:  Biometrics     Country:  United States    
Other Details:
Languages:  eng     Pagination:  715-23     Citation Subset:  IM    
Affiliation:
Department of Medical Statistics, Medical University of Vienna, Schwarzspaniesrstr. 17, Vienna, Austria. werner.brannath@meduniwien.ac.at
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MeSH Terms
Descriptor/Qualifier:
Biometry
Clinical Trials as Topic / statistics & numerical data*
Data Interpretation, Statistical
Effect Modifiers (Epidemiology)
Guanidines / therapeutic use
Humans
Likelihood Functions
Models, Statistical
Myocardial Infarction / drug therapy
Randomized Controlled Trials as Topic / statistics & numerical data
Sample Size
Sulfones / therapeutic use
Chemical
Reg. No./Substance:
0/EMD 96785; 0/Guanidines; 0/Sulfones

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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