Bioequivalence and Bioavailability Forum • Oops!

Oops! [Two-Stage / GS Designs]

posted by d_labes – Berlin, Germany, 2011-02-07 17:29 (5194 d 00:00 ago) – Posting: # 6569
Views: 26,235

Dear Helmut,

❝ good question, next question!

It was the best question I had at moment :-D

. But may be later on I have some better.

❝ ... No idea how Potvin et al. got their values.

According to their formula given in paragraph 2.3 they use the approximation via central shifted Student's t-distribution, shortly described in the accompanying material of package PowerTOST.
Check it via the undocumented and hidden function :cool:

.approx2.power.TOST(alpha=0.05, se=sqrt(0.020977), diffm=log(0.95), 

                    ltheta1=log(0.8),ltheta2=log(1.25), n=12, df=10, bk=2)

>[1] 0.8412397

.approx2.power.TOST(alpha=0.0294, se=sqrt(0.020977), diffm=log(0.95), 

                    ltheta1=log(0.8),ltheta2=log(1.25), n=12, df=10, bk=2)

>[1] 0.7561472

But what you discuss was not my point, I think. Or was your first sentence already the answer?
I need to know the power of Potvin B/C if I assume 'true' GMR=1.08, 'true' CV = 0.3 for instance. What to do with the steps in the decision scheme

Check the power using an alpha ...
calculate sample size using an alpha ...

which were done in Potvin et.al. with GMR=0.95?
Stay with 0.95 or replace with 1.08?

—
Regards,

Detlew

Complete thread:

Potvin method B subtleties d_labes 2011-01-31 14:24 [Two-Stage / GS Designs]
- Potvin method B subtleties jdetlor 2011-02-01 17:17
  - Potvin method B subtleties d_labes 2011-02-02 09:15
    - Potvin method B subtleties jdetlor 2011-02-02 16:08
      - Gould d_labes 2011-02-02 16:25
        
        Gould jdetlor 2011-02-02 17:02
- Another one ... d_labes 2011-02-07 14:32
  - Oops! Helmut 2011-02-07 15:24
    - Oops!d_labes 2011-02-07 16:29
      - Oops! Helmut 2011-02-07 16:47
        
        Oops! ElMaestro 2011-02-07 17:06
        
        Oops! Helmut 2011-02-07 17:17
        
        Oops! ElMaestro 2011-02-07 18:35
        
        Simul'ants in my pants d_labes 2011-02-08 09:07
        
        Need for speed... ElMaestro 2011-02-13 10:57
        
        Need for speed... d_labes 2011-02-15 14:06
        
        Need for speed... ElMaestro 2011-02-15 17:39
        
        Pocock alpha's d_labes 2011-02-16 09:18
        
        ElMaestro's brain ElMaestro 2011-02-16 09:32
        
        ElMaestro's brain d_labes 2011-02-16 10:05
        
        ElMaestro's brain ElMaestro 2011-02-16 12:07
        
        Numbers d_labes 2011-02-16 13:45
- Bonus counter-question ElMaestro 2011-02-07 23:44
  - Speed is the question d_labes 2011-02-08 08:36
- New paper (method D for PE 0.90) Helmut 2011-04-18 12:58
  - New paper (method D for PE 0.90) d_labes 2011-04-19 08:58
    - New paper (method D for PE 0.90) Helmut 2011-04-19 14:30
    - New paper (method D for PE 0.90) ElMaestro 2011-04-19 14:49
      - Stopping criterion # futility rule Helmut 2011-04-19 15:28