Bioequivalence and Bioavailability Forum

Dear Sathya,

To summarise: calculating post-hoc power makes no sense and has no interest in BE trials. Unless it is specifically requested by the guideline of the country in which you intend to submit your trial data, just forget about it and stop losing your time trying to calculate it.

The only question once your trial is completed is: is bioequivalence demonstrated or not ? Whether your 90 % CI is included within 80-125 with 60 % power or 95 % power makes no difference in the end: you demonstrated bioequivalence, that's all ! You were just more lucky not to fail in the first case. That's why we are calculating 90 % CI and not trying to show a difference between formulations. The alpha risk is fixed and is the patient's risk; the beta risk is for the sponsor.

If you failed to demonstrate bioequivalence, then you can start wondering whether you had enough power to demonstrate it. But here again calculating post-hoc power is of no interest: rather check whether your pre-study assumptions used to calculate the number of subjects were valid or not (difference between test and reference, intra-subject CV in a cross-over study).

Regards
Ohlbe