Bioequivalence and Bioavailability Forum

Unequal CVs [Power / Sample Size]

posted by d_labes  – Berlin, Germany, 2013-02-15 09:47 (4877 d 09:31 ago) – Posting: # 10027
Views: 12,728

Dear Helmut,

a follow up to your post:

❝ I like the option to specify unequal CVs of test and reference as CV=c(T,R). Example for EMA, 3-period, T/R 0.95, 80% power (pooled CV_intra 0.3 in all cases):

❝   CVWT     CVWR   n


❝  0.2500  0.3458  24
❝  .....

❝ It will pay off to have a ‘better’ formulation.

This is what one would expect. I least I think I had read something like that in SABE papers.

[nitpicking] But I doubt that your chosen CVs give a pooled CV of 0.3.
As a one-liner using the PowerTOST helper functions I got:
mse2CV(mean(CV2mse(c(0.25,0.3458))))
[1] 0.3011071.
[/nitpicking]

What did the one-liner do? Calculate the intra-subject variances for T and R, calculate the mean of both and back-calculate from that mean the CV .

Or did I miss somefink Welch here?

Complete thread:

• Sample size for RSABE Anu 2013-02-01 07:01 
  • Sample size for RSABE d_labes 2013-02-01 09:46
    • Sample size for RSABE Anu 2013-02-07 06:58
      • No analytic solution! Helmut 2013-02-07 12:32
        • Coming soon ... d_labes 2013-02-08 11:57
          • Wow! Helmut 2013-02-08 12:19
            • Wow! Anu 2013-02-09 09:20
              • read… Helmut 2013-02-09 09:35
            • Bigamist d_labes 2013-02-09 18:11
              • Some testing (Part I) Helmut 2013-02-10 18:35
              • Some testing (Part II) Helmut 2013-02-11 01:00
                • Power testing d_labes 2013-02-11 12:03
                  • the unknown x Helmut 2013-02-11 14:40
                • Unequal CVsd_labes 2013-02-15 08:47
                  • Typo Helmut 2013-02-15 13:01