Bioequivalence and Bioavailability Forum • Small is beautiful

Small is beautiful [🇷 for BE/BA]

posted by Helmut – Vienna, Austria, 2010-06-15 18:54 (5484 d 20:20 ago) – Posting: # 5524
Views: 12,403

Dear D. Labes!

❝ Let me expand your table: ...

❝ Is this what you expected to see?

Not really. Of course the estimate approaches asymptotically the fixed value, but I expected some kind of award for performing a larger pilot study. A larger pilot gives me a 'better' estimate and therefore the size of the main study will be smaller. But if I add the sample sizes of pilot and main studies, I'm disapointed. See the end of my post.

❝ Of course this tells us a well known study: Pilots with smaller than 12 subjects are not very useful.

OK, right - common sense, supported by PowerTOST. It's interesting that there is a minimum total sample size - very useful!

❝ For your second concern

❝ ❝ for higher CVs, the size of the pilot study becomes more and more irrelevant?!

❝ I do not get exactly your point. "Small" and "large" pilot study is not so well defined here I think.

Let's look at the 30% CV example. If the pilot study had 12 subjects I would plan the main study for 48. In a 24 pilot I get a better estimate and plan the main in only 42. But I'm punished, because the total sample size (pilot+main) will be 66 instead of 60. This speaks against my pet hypothesis. I learned from your table that there seems to be an optimal pilot sample size (if the total size is concerned), namely for CV 20% 8-10, CV 25% 10-12, CV 30% 12-14, and CV 35% 14-16...

❝ BTW: Be so kind and enlighten a non-latin educated person about Sancta.

Invocationing Guru Stephen in English: Saint Juliuos, stay by me!

—
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Helmut Schütz

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Complete thread:

PowerTOST & beyond Helmut 2010-06-11 18:08
- Small is beautiful d_labes 2010-06-15 15:25
  - Small is beautifulHelmut 2010-06-15 16:54
    - Small is beautiful Alice 2010-07-14 14:32
      - Small is beautiful Helmut 2010-07-14 16:23
        
        Small is beautiful Alice 2010-07-15 21:35
        
        Small is beautiful Helmut 2010-07-16 00:14
        
        Small is beautiful Alice 2010-07-19 21:57
        
        Biometrika Helmut 2010-07-26 02:01
      - Power to the students d_labes 2010-07-15 10:41
        
        Power to the students Alice 2010-07-15 21:55
        
        Power to the studentinnen d_labes 2010-07-16 12:56
        
        Power to the studentinnen Alice 2010-07-19 22:17
        
        Coming soon ... d_labes 2010-07-26 13:59