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Activity Number:
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213
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Type:
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Contributed
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Date/Time:
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Tuesday, August 13, 2002 : 10:30 AM to 12:20 PM
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Sponsor:
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Biometrics Section*
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| Abstract - #301850 |
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Title:
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An Efficient Method of Subgrouping in Crossover Trials and its Performance Evaluation by Simulations
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Author(s):
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Heather Crosby*+ and Subir Ghosh
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Affiliation(s):
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University of California, Riverside
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Address:
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3578 Nelson Street, Riverside, California, 92506-3012, USA
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Keywords:
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clinical trials ; crossover design ; subgrouping ; critical adjacent factor ; simulations ; gap values
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Abstract:
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We present an efficient method of subgrouping of subjects in a group for crossover trials. This method is an improvement over the method described in Ghosh and Fairchild (2000). This method is based on a Threshold Level, a Critical Adjacent Factor (CAF), and a Majority Rule. We present two performance measures for evaluating this method. The first performance measure is the probability of identifying the correct number of subgroups. The second performance measure is the probability that a subject is correctly placed in a subgroup in a situation where the number of subgroups has been correctly identified. The optimum CAF values are obtained by maximizing the first performance measure and then refining the optimal choice of CAF by using the second performance measure. We present extensive simulation results for the purpose of evaluating the proposed method for various values of the noise parameters. Our effort is successful in improving the procedure of subgrouping in crossover trials.
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