On sample size calculation in bioequivalence trials

Sample size calculation plays an important role in bioequivalence trials. I n practice, a bioequivalence study is usually conducted under a crossover d esign or a parallel design with raw data or log-transformed data. In this p aper, we discuss the differences in sample size calculation between a cross over design and a parallel design with raw data ol log-transformed data. Fo rmulas for sample size calculation under a crossover design and a parallel design with raw data or log-transformed data are derived. A brief discussio n for the relationship among these formulas is given.