Bioequivalence and Bioavailability Forum

Small is beautiful [🇷 for BE/BA]

posted by d_labes  – Berlin, Germany, 2010-06-15 17:25 (5431 d 09:01 ago) – Posting: # 5516
Views: 12,034
(edited on 2010-06-16 08:28)

Dear Helmut,

thanks for playing with that tool. If the man plays he is well .

Very interesting observation!

Let me expand your table:
         CV = 20%   CV = 25%    CV = 30%    CV = 35%
 pilot  main total main total  main total  main total
   6     32   38     50   56     68   74     96  102
   8     26   34     40   48     56   64     78   86
  10     24   34     36   46     52   62     72   82
  12     24   36     34   46     48   60     64   76
  14     22   36     34   48     46   60     62   76
  16     22   38     32   48     46   62     60   76
  18     22   40     32   50     44   62     58   76
  20     22   42     32   52     44   64     58   78
  22     22   44     32   54     44   66     58   80
  24     20   44     30   54     42   66     56   80
  ...    ...         ...         ...         ...
  inf    20  inf     28  inf     40  inf     52  inf

Is this what you expected to see?

Of course this tells us a well known story: Pilots with smaller than 12 subjects are not very useful.
But more then 24 subjects are also not recommendable with respect to the total sample size.
But this is only true if you take the uncertainty of the CV into account. Else you may end in an underpowered study.

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.

❝ Shall I abandon my pet hypothesis and suggest "the smaller, the better" in the future?

I think there is no sound reason to do so. Also there is some rumor out there: "Small is beautiful" .

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

Complete thread:

• PowerTOST & beyond Helmut 2010-06-11 18:08 
  • Small is beautifuld_labes 2010-06-15 15:25
    • Small is beautiful Helmut 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