## Two-Stage Sequential Potvin Designs [Two-Stage / GS Designs]

Helmut and ElMaestro,

❝ I guess you are thinking about scaled average bioequvalence (ABEL or RSABE)? How would you find a suitable one? For the type I error you need 106 simulations. Doable in a 2×2×2 and parallel design because there is an exact formula for power. Multiply that with the number of grid points. Takes some time, but OK. On the contrary in SABE there is no analytical solution for power and we need 105 simulations for the sample size re-estimation of every grid point. See this article. Good luck!

Yes, I was thinking about ABEL. Thanks for the link to the article, I havent come across this postscritp, very useful!

❝ There is a paper about running a stage 1 with two test formulations. Then picking the best one and doing stage 2 with it. I think it was some Danish weirdo who published it. That wasn't a replicate design, though.

Thanks, I have found it and read it. Great paper with great explanations!
I just have a question regarding 1st stage study(ies) here. If I am not mistaken, the paper describes two studies in the 1st stage - each with their own test formulation (A or B + reference) ("At the end of the day, even though the two trials at stage 1 are conducted as 2-treatment, 2-sequence, 2-period trials").
Could we also perform one study in the 1st stage with 2 test treatments (so 3-treatment, 6-sequence, 3-period) instead of 2 studies seperately? But then probably all of these calculations (alphas, TIE, power...) mentioned in the article wouldnt apply? Or would they?

In the paper you calculated power and alphas for different combinations of CV (0.1-1.0 by 0.1), N (12, 24, 36, 48 and 60) and GMR. So if one goes into a 1st stage with any deviations from these combinations (for example N1=20 or CV=0.25), one would have to perform additional simulations with this combination?

BEQool