Bioequivalence and Bioavailability Forum • Potvin B, C, or D?

Potvin B, C, or D? [Two-Stage / GS Designs]

posted by Helmut – Vienna, Austria, 2011-10-28 00:52 (5342 d 03:23 ago) – Posting: # 7557
Views: 21,854

Dear D. Labes!

❝ ❝ Why don't we discuss method C in stead where the authors make a clear discussion between alpha1 and alpha2; it is for many practical purposes performing just like method B anyway, at least under the conditions tested by Potvin :-D .

❝

❝ I can not see the 'clear discussion' for alpha1 and alpha2 in the Potvin et al. paper.

Me not either. I’ve heard that regulators read this forum; so if they have no access to the paper here’s a snippet from its Section 5 (Discussion and Recommendations)

The goal of our group was to validate at least one method for two-stage designs that could be used for BE studies. Methods B and C meet our criteria of not more than minimal inﬂation of type I error rate. We recommend that regulatory agencies accept either. It is our understanding that the FDA has accepted studies with designs like those considered here.
For sponsors, there is a small power advantage to Method C over Method B, so we consider Method C as the method of choice. Another advantage of Method C is that it was designed so that if the study were found to have adequate power at the ﬁrst stage, the α for that study would be the same as if it were designed to be single-stage study.

❝ For the acceptance of Potvin C see this post.

Terrible.
BTW, FDA recommends Method C (for T/R 0.95) and Method D (for T/R 0.90)… That’s not surprising with Donald Schuirmann as a co-author.

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Complete thread:

2-stage design - power evaluation d_labes 2011-10-12 11:10
- No opinions out there? d_labes 2011-10-26 09:14
  - Opinion yes, answer no ElMaestro 2011-10-26 11:15
    - Decision scheme without (?) power check d_labes 2011-10-26 13:00
      - Decision scheme without (?) power check ElMaestro 2011-10-26 13:20
        
        Decision scheme 'without' power check d_labes 2011-10-26 14:51
        
        Decision scheme 'without' power check ElMaestro 2011-10-26 15:24
        
        Numerical example d_labes 2011-10-26 16:28
        
        Numerical example ElMaestro 2011-10-26 16:49
        
        Potvin C with unsymmetrical alphas d_labes 2011-10-27 14:54
        
        Potvin B, C, or D?Helmut 2011-10-27 22:52
        Two-stage (classical Pocock) and the FDA Helmut 2011-10-31 02:36
- Weirdo paper ElMaestro 2011-11-30 18:04
  - Weirdo paper Helmut 2011-11-30 23:45
    - Weirdo paper ElMaestro 2011-12-01 07:16