Bioequivalence and Bioavailability Forum

Dear rafimmc!

❝ Can you please explain the study designs of add-on and group sequential. I couldn't understand the difference between these two study designs.

See my last post:

❝ In an Add-On design you don't adjust α; in a sequential design you are penalized for the ‘first look’, the α-level at each level depends on the stagewise sample size ratio n1:n2, and on the strategy for implementing the design (93–94% nominal CIs are common to maintain the overall type I error 0.05).

For an Add-on have a look at Section 7.4.2 of the Canadian Guideline, for a sequential design please read Gould’s paper (not only the abstract).

Details would go beyond the scope of the forum (or at least anything I would do in my free-time, maybe somebody else is willing to jump in); please consult with a biostatistician experienced in the field of BE.