Bioequivalence and Bioavailability Forum

Dear Shuanghe, dear Helmut!

The whole thing you discuss here is a pure tragedy.
Such a lot of ignorance to scientific work and results is unbelievable .
I'm at loss for words.

Regarding the intermediate power calculations:

Of course you can formulate the Potvin's decision scheme B without them.
But then it will happen that the sample size estimation step will give you a number which is smaller or at best equal to that you have already used for step 1.

Now what then?
Natural would be: STOP study. Bioequivalence not proven!
Exactly this is what the intermediate power calculation is for in scheme B.

I've heard some rumour from regulators that you should not stop but recruit 2 more subjects for stage 2 in that case. But this lacks any scientific justification IMHO.

Scheme C (D) is more complicated. At moment I don't have any idea if one can formulate it without intermediate power calculation. Seems a very integral part of that scheme.