Bioequivalence and Bioavailability Forum • Advantages

Advantages [Two-Stage / GS Designs]

posted by ElMaestro – Denmark, 2015-06-05 12:07 (3579 d 04:32 ago) – Posting: # 14915
Views: 19,530

Hi all,

❝ sample size p stop at

❝ CV alpha's power mean p95% interim

❝ --------------------------------------------

❝ 0.15 Poc 88.13% 13.5 22 79.3%

❝ adjHP 88.32% 14.2 22 56.2%

❝ 0.25 Poc 81.17% 32.3 60 18.6%

❝ adjHP 79.91% 30.5 54 3.9%

❝ 0.4 Poc 74.95% 78.8 142 1.0%

❝ adjHP 75.18% 70.5 128 0.1%

❝ 0.7 Poc 72.42% 207.3 378 0%

❝ adjHP 72.93% 185.1 338 0%

❝ (...) Judging this as advantage or practically not is up to you :cool: .

This is a good example showing how complex the issue is.
Around CV=0.25 in this example the Pocock alphas performs better in terms of power than HP, and with a little higher sample size. CV is never known in advance of the experiment but the region of CV=0.25 is where most drugs (drug products) happen to be.

We really need some kind of summary statistic that is the ultimate indicator of whether one method is better than the other. Power divided by Avg Sample size would be my own best initial guess (to me this would be the bang you get for your buck)
I₁=pwr/N_avg

Or perhaps better:

I₂=(pwr-0.7)/N_avg

The more positive I₂ the better, something like that. Negative I₂ would possibly just go directly into the waste bin as I can't imagine anyone would be interested in a power lower than 0.7 or thereabouts (0.7 is taken a litle out of the blue, but I am noting that Potvin's methods all have power>0.7 for targetP=0.8).

Let me hear your opinion, do you have some ideas for a summary statistic that would help us decide between the various methods and versions?

PS: Perhaps this Q should be moved into its own separate thread?

—
Pass or fail!
ElMaestro

Complete thread:

Does unequal alpha distribution make sense? Dr_Dan 2015-05-19 08:29 [Two-Stage / GS Designs]
- Maybe; but watch the TIE! Helmut 2015-05-28 15:04
  - Advantages d_labes 2015-06-05 09:35
    - AdvantagesElMaestro 2015-06-05 10:07
      - Advantages – performance measure d_labes 2015-06-05 11:21
        
        Advantages – performance measure Helmut 2015-06-05 13:29
        
        Advantages – performance measure d_labes 2015-06-05 21:27
        
        Advantages – performance measure Helmut 2015-06-05 23:29
        
        Histogram wonder d_labes 2015-06-06 12:58
        
        Histogram charlatanry Helmut 2015-06-09 13:43
        
        Histogram beauty d_labes 2015-06-09 14:55
        
        Histogram beast Helmut 2015-06-09 15:24
- Does unequal alpha distribution make sense? Dr_Dan 2015-05-29 08:33
  - Does unequal alpha distribution make sense? ElMaestro 2015-05-29 09:31
    - Does unequal alpha distribution make sense? nobody 2015-05-29 12:56
      - Old beliefs die hard Helmut 2015-05-29 13:27
        
        Old beliefs die hard nobody 2015-05-29 13:41
        
        Old beliefs die hard Helmut 2015-05-29 18:08
        
        Old beliefs die hard ElMaestro 2015-05-29 18:57
        
        Old beliefs die hard nobody 2015-05-29 20:06
        ♩ ♪♫♬`·.¸¸.·´`·.¸¸. Helmut 2015-06-02 01:52
        
        TSD only an option in exceptional cases Dr_Dan 2015-06-02 08:00
        
        TSD only an option in exceptional cases nobody 2015-06-02 09:23
        
        OT Helmut 2015-06-02 12:07
        
        OT nobody 2015-06-02 12:41
- Banana splits Helmut 2015-06-02 00:48