Bioequivalence and Bioavailability Forum

Simul Ants questions [Regulatives / Guidelines]

posted by ElMaestro  – Denmark, 2011-11-04 17:06 (4930 d 02:49 ago) – Posting: # 7608
Views: 8,994

Hi d_labes,

❝ Really?

❝ I would suggest:

❝ If you consider 95, 90 and 110 as the arithmetic means on the untransformed scale use log(x)-sd²/2 as the mean of the logs.

❝ If your numbers 0.15, 0.10 and 0.15 are the CV's user sd = sqrt(log(CV*CV+1)) as sd of the logs.

I think Martin raised this before. I don't understand this aspect. Feel free to educate me, you great scientist!

❝ The manner you have written the simulation for the three treatments suggest you consider the log(metric) for the 3 treatments as independent.

❝ Is this really the case for a cross-over where the 3 treatment were applied to each subject ? IMHO we have to consider some correlation between them.

Probably a good point. But let's take the simple 2,2,2-BE scenario as example. Treatmeant T and R is probably correlated within patients; but we still only work with a covariance matrix with a single sigma squared on the diagonal and zeros elsewhere. I don't know how to take any such correlation into effect, but if you wish to do it a way forward might be a mixed model.

As you can see above the original code was something I wrote 20 months ago, and I am today questioning my sanity back then. Actually I am still bonkers, but I guess that's another matter .

EM.

Complete thread:

• Anticonservativism?! ElMaestro 2010-02-06 17:10 [Regulatives / Guidelines] 
  • Conservativism? Helmut 2011-11-03 21:12
    • In hindsight... ElMaestro 2011-11-03 21:43
      • In hindsight... Helmut 2011-11-04 01:56
        • In hindsight... ElMaestro 2011-11-04 08:41
        • rlnorm simulates what? d_labes 2011-11-04 09:40
          • Oops. Helmut 2011-11-04 16:05
            • Oops. ElMaestro 2011-11-04 16:22
              • Simulation of intra-subject variability d_labes 2011-11-07 11:16
                • Simulation of intra-subject variability ElMaestro 2011-11-08 11:02
            • Oops. Oops. d_labes 2011-11-25 13:54
              • Another Oops. Helmut 2011-11-25 14:23
  • Simul Ants questions d_labes 2011-11-04 15:46
    • Simul Ants questionsElMaestro 2011-11-04 16:06
    • Simul Ants questions Helmut 2011-11-04 16:09
  • Liberal Conservatives d_labes 2011-11-08 11:31
    • Liberal Conservatives martin 2011-11-08 20:50
      • Liberal Conservatives Helmut 2011-11-08 22:56
        • intra-subject correlation martin 2011-11-09 09:01
          • intra-subject correlation Helmut 2011-11-25 17:16