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Sample Size Adjustment in Clinical Trials for Proving Equivalence

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Abstract

To overcome the problem of uncertainty in the planning phase of clinical trials, study designs have been proposed that allow for mid-course reestimation of the sample size. Using a study in asthma patients, we illustrate how blind sample size adjustment can be performed in an equivalence trial. Thereby, we demonstrate how the type I error rate can be controlled. Further, we show that the well-known expectation-maximization algorithm-based procedure by Gould and Shih is inappropriate for the purpose of sample size reestimation.

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Author information

Correspondence to Dr. Meinhard Kieser PhD.

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Friede, T., Kieser, M. Sample Size Adjustment in Clinical Trials for Proving Equivalence. Ther Innov Regul Sci 35, 1401–1408 (2001) doi:10.1177/009286150103500436

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Key Words

  • Interim analysis
  • Sample size review
  • Sample size adjustment
  • Equivalence trial
  • Control of the type I error rate