Bioequivalence and Bioavailability Forum

Hi Dr_Dan,

apart from what Helmut said, I'd like to add that unless we somehow fix sample size at stage 2 so that it is equal to sample size at stage 1 we could have subjects for whom there is data for one stage and subjects for whom there is data from two stages. This is complicated to handle from a covariance perspective.
And if we fix sample size at stage 2 so that it equals sample size at stage 1 then my gut feeling tells me that we might too easily get a low power cf. futility rules for ordinary two-stage designs.