Bioequivalence and Bioavailability Forum • A posteriori power

A posteriori power - No.666 [Power / Sample Size]

posted by Helmut – Vienna, Austria, 2011-03-08 15:27 (5592 d 19:08 ago) – Posting: # 6724
Views: 8,402

Dear Marcel!

❝ During a pilot study, we obtained intra-subject CV about half of what is now published, so this authority basically is saying that we underpowered the study because the CV we obtained is not possible.

Not possible‽ What were the CVs actually?

Published one(s)
Your pilot study
Your pivotal study

❝ Having read your presentation, I can see why pilot info isn’t all that great for sample size estimation.

I wouldn’t say that. Only in a pilot study you can control everything (clinical setting, blood sampling time points, bioanalytical method,…). If I have the chance to choose I would always opt for a pilot study. But the size shouldn’t be too small and the CV_intra not taken literally (allowing for a safety margin). In the future you might consider a Two-Stage design...

❝ Day 210 is tomorrow, so we'll likely get referred to CMD.

Good luck!

—
Dif-tor heh smusma 🖖🏼 Довге життя Україна!
Helmut Schütz

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Complete thread:

Consumer risk Marcel 2011-03-08 10:56 [Power / Sample Size]
- Consumer risk ElMaestro 2011-03-08 11:30
  - Consumer risk Marcel 2011-03-08 12:01
    - Consumer risk ElMaestro 2011-03-08 12:13
    - A posteriori power - No.666 Helmut 2011-03-08 12:27
      - A posteriori power - No.666 Marcel 2011-03-08 12:50
        
        A posteriori power - No.666 ElMaestro 2011-03-08 13:06
        A posteriori power - No.666 Helmut 2011-03-08 13:41
        
        A posteriori power - No.666 Marcel 2011-03-08 14:13
        
        A posteriori power - No.666Helmut 2011-03-08 14:27
        
        A posteriori power - No.666 Marcel 2011-03-08 14:49
        
        A posteriori power - No.666 Helmut 2011-03-08 15:03
        
        A posteriori power - No.666 Marcel 2011-03-08 15:28
        
        ... ElMaestro 2011-03-09 23:16