α and 1–β [Power / Sample Size]

posted by Helmut Homepage – Vienna, Austria, 2017-12-27 12:57  – Posting: # 18099
Views: 25,692

Hi Yura,

» If at GMR=0.95 and CV=0.25 calculation has to be carried out at N = 28-30 subjects, and you carry out on 50 subjects, there can be questions on forced bioequivalence :cool:

If I got your example correctly, 28–30 subjects mean 81–83% power. In some guidelines 80–90% power are recommended. 90% power would require 38 subjects. 50 subjects would mean 96% power (BE-proff’s “big wallet”).
However, such a sample size should concern only the IEC (assessing the risk for the study participants). If the protocol was approved by the IEC and the competent regulatory agency, performed as planned and by chance show an even higher “power”, an eyebrow of the assessor might be raised but technically (Type I Error is controlled) there is no reason to question the study.

Cheers,
Helmut Schütz
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