Abstract
In recent years, quantitative evaluation for biosimilarity has been taken seriously due to the development of biosimilar products. The concept for assessment of biological products is very different from that of small-molecule drug products because of the variability with respect to the manufacturing process and environmental factors of the biological products. In this article, we propose an estimate method for a biosimilar index and the related lower bound based on the concept of reproducibility probability by assessing power. In addition, some approximations are proposed and compared in regard to simplicity and accuracy.