Bioequivalence and Bioavailability Forum • Nonbinding futility rule

Nonbinding futility rule [Two-Stage / GS Designs]

posted by d_labes – Berlin, Germany, 2018-06-14 12:47 (2136 d 14:43 ago) – Posting: # 18906
Views: 15,394

Dear Ben,

❝ The reference at page 19 actually refers to the CI futility criterion,

I know.

❝ ... in my opinion the only possibility is: if you want to be able to handle it in a nonbinding manner, then you have to go with conditional error rates only (i.e. you cannot use the estimated conditional target power as target power for calculation of n2). So, we would need to select ssr.conditional = "error".

My first thought was: Set fCpower = 1, that results in do not use the power futility criterion. This gives n2=16 for mittyri's example
interim.tsd.in(GMR1=0.89, CV1=0.2575165, n1=38, fCpower=1).

Your suggestion
interim.tsd.in(GMR1=0.89, CV1=0.2575165, n1=38, ssr.conditional = "error")
gives also n2=16. Astonishing or correct?

Avoiding the conditional sample size re-estimation, i.e. using the conventional sample size re-estimation via
interim.tsd.in(GMR1=0.89, CV1=0.2575165, n1=38, ssr.conditional = "no")
gives n2=4. Ooops? Wow!

Helmuts caveat of how to decide in case of "nonbinding futility" needs to be considered, scientifically, not via NLYW :-D

.
IIRC the term "nonbinding" in the context of sequential designs is used for flexibility in stopping or continuing due to external reasons. Do we have such here?

Binding, nonbinding - does it have an impact on the alpha control? I think not, but are not totally sure.

—
Regards,

Detlew

Complete thread:

Finally: Exact TSD methods for 2×2 crossover designs Helmut 2018-04-21 17:17 [Two-Stage / GS Designs]
- Exact TSD methods: Example Helmut 2018-04-21 20:33
- Finally: Exact TSD methods for 2×2 crossover designs ElMaestro 2018-04-21 20:49
  - Flow chart (without details) Helmut 2018-04-21 21:41
    - naive questions regarding new functions in Power2Stage mittyri 2018-04-28 15:54
      - Some answers Helmut 2018-04-28 17:29
      - Some more "answers" d_labes 2018-04-29 21:11
        
        clarification regarding user Power2Stage guides mittyri 2018-04-30 13:41
- Technicality: Weigths for the inverse normal approach d_labes 2018-04-25 14:19
  - Selection of w and w* Helmut 2018-04-26 09:51
    - Selection of w and w* d_labes 2018-04-26 20:02
    - Now what? w & w* examples d_labes 2018-05-09 13:53
      - Now what? w & w* examples Ben 2018-06-10 20:12
        
        Now what? w & w* examples Helmut 2018-06-11 13:57
        
        Now what? w & w* examples Ben 2018-06-12 19:14
        
        a bug in interim.tsd.in()? mittyri 2018-06-11 23:27
        
        a bug in interim.tsd.in()? Ben 2018-06-12 19:32
        
        Nonbinding futility rule d_labes 2018-06-13 16:59
        
        Bad weather? Helmut 2018-06-13 19:23
        
        NLYW? d_labes 2018-06-14 10:18
        
        Nonbinding futility rule Ben 2018-06-13 20:26
        
        Nonbinding futility ruled_labes 2018-06-14 10:47
        
        Nonbinding futility rule Ben 2018-06-15 17:58
        
        Binding / Nonbinding futility rule - alpha control d_labes 2018-06-16 19:42
        
        Binding / Nonbinding futility rule - alpha control Ben 2019-03-30 09:52