Bioequivalence and Bioavailability Forum

Simul Ants questions [Regulatives / Guidelines]

posted by d_labes  – Berlin, Germany, 2011-11-04 16:46 (4930 d 06:52 ago) – Posting: # 7606
Views: 8,939

Dear EM,

❝ load(nlme)


 nConservative=0
 nAntiConservative=0
 
 ...
 for (iter in 1:100)
 {
 
 ## T is 1, R1 is 2 and R2 is 3
 lny1 = rnorm(n=36, mean=95, sd=0.15*95)
 for (i in 1:36) if (trt1[i]==2) lny1[i]=rnorm(n=1, mean = 90, sd = 0.10*90)
 for (i in 1:36) if (trt1[i]==3) lny1[i]=rnorm(n=1, mean = 110, sd = 0.15*110)
 ...

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.

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.

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 questionsd_labes 2011-11-04 15:46
    • Simul Ants questions ElMaestro 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