Bioequivalence and Bioavailability Forum • A posteriori power

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

posted by Helmut – Vienna, Austria, 2011-03-08 14:41 (5589 d 11:52 ago) – Posting: # 6722
Views: 8,336

Dear Marcel!

❝ ❝ The CMS was not by any chance Greece?

❝

❝ They still do, but they withdrew their objection (it was in a different DCP).

Unbelievable! :crying:

❝ I pointed to a paper by Hoenig and Hensey you also quote at the end of your presentation [...]. But they just tried to use it against us, but I couldn't follow their logic, since it basically contradicted their stance that post hoc power has meaning.

❝

❝ This is the wording they are using: The reduced number of the enrolled subject confers to the study a weak perspective power (just above 0.5). Therefore the BE evaluation could not be reliable.

Crazy. I guess you planned (!) for power of ≥80% and suffered from one of the followings (or any combination thereof)?

CV_intra higher than expected,
higher drop-out rate than anticipated,
T/R deviating more from 1 than expected.

BTW, if you look at power curves #1 and #2 are less painful than #3…

I’m not sure what they mean by:

❝ The reduced number of the enrolled subject...

I hope you suffered from #2 above. If you really enrolled less subjects than planned, this might be of ethical concerns - but still does not invalidate the study.

❝ I'm trying to figure out if they are talking about producer or consumer risk here.

Likely about the former. The latter is fixed at 5% (see ElMaestro’s nice answer).

❝ Therefore the BE evaluation could not be reliable.

Nuts! If you initiated the study with power “just above 0.5” that’s bad practice. You took a high risk of failure – and succeeded. If you were a victim of #2 nothing to worry about.

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

The quality of responses received is directly proportional to the quality of the question asked. 🚮
Science Quotes

Complete thread:

Consumer risk Marcel 2011-03-08 10:56
- 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.666Helmut 2011-03-08 13:41
        
        A posteriori power - No.666 Marcel 2011-03-08 14:13
        
        A posteriori power - No.666 Helmut 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