Bioequivalence and Bioavailability Forum

Hello BEman,

❝ What do you think about such an approach?

❝ Do you have any experience with authority concerning this issue?

❝ Does the penalty assignment to the stages keeps the 'overall' type 1 error of the study under control?

❝ Do you know literature about an alpha-spending function, which i can use to calculate such extreme alpha spending described above?

This is not a good approach ethically. Even though you may have control over your alpha the power becomes easily surprisingly low if you implement stopping rules based on stage 2 size. I think such trials are possibly futile and thus not ethical.
I am not sure regulators know this (yet?) because it requires simulation software to figure it out. There is no published paper about it as far as I know.