Bioequivalence and Bioavailability Forum • Precision of PowerTOST

Precision of PowerTOST [Power / Sample Size]

posted by mittyri – Russia, 2017-12-09 22:05 (1935 d 09:31 ago) – Posting: # 18050
Views: 13,165

Hi Helmut,

sorry if my thoughts were unclear in previous post.
As Astea has noted, 2 Laszlos in their paper estimated the required minimum sample size as 54 subjects for "2x3x3" design (CV=0.8, theta0=0.95). They claimed that "The precision of the estimation was evaluated by running the simulations twenty times".
My question was: is it possible for PowerTOST? Is it possible to get the mean power of 80% using the mean of 20 runs?


library("ggplot2")

library("PowerTOST")

reps <- 1E4

scABELoverall <- data.frame(rep = 1:reps)

scABEL20 <- data.frame(1:20)

for(external in 1:reps){

  for(internal in 1:20){

    scABEL20$power[internal] <- power.scABEL(CV=0.8, n=54, theta0=0.95, design="2x3x3", nsims=10000, setseed=F)

  }

  scABELoverall$meanpower[external] <- mean(scABEL20$power)

}

ggplot(scABELoverall, aes(meanpower))+

  geom_density(fill = 2, alpha = 0.3)+

  theme_bw()+

  ggtitle(sprintf("%d reps: Mean is %.4f, SD is %.4f; %.2f %% of twenties are less than 0.8", reps, mean(scABELoverall$meanpower), sd(scABELoverall$meanpower), sum(scABELoverall$meanpower<0.8)/length(scABELoverall$meanpower)*100))

So the answer is: yes, that's possible, but you need to be unlucky (the probability is about 7%) :-D

—
Kind regards,
Mittyri

Complete thread:

Sample Size Estimation -Replicate design- BE limits cakhatri 2017-11-30 09:44 [Power / Sample Size]
- Reference-scaling: Don’t use FARTSSIE! Helmut 2017-11-30 10:58
  - Reference-scaling: Don’t use FARTSSIE? Astea 2017-11-30 22:50
    - Reference-scaling: Don’t use FARTSSIE! Helmut 2017-12-01 11:42
      - Reference-scaling: USE PowerTOST Astea 2017-12-01 14:16
        
        Reference-scaling: USE PowerTOST cakhatri 2017-12-04 06:00
        
        Reference-scaling: USE PowerTOST Helmut 2017-12-04 15:07
        
        Reference-scaling: USE PowerTOST cakhatri 2017-12-05 05:33
        
        Use PowerTOST d_labes 2017-12-06 09:52
        
        Use PowerTOST, not Endrényi L, Tóthfalusi L tables mittyri 2017-12-07 16:03
        
        Precision in Endrényi L, Tóthfalusi L tables d_labes 2017-12-07 18:21
        
        Precision of PowerTOST mittyri 2017-12-08 22:56
        
        Precision of PowerTOST Helmut 2017-12-09 17:00
        
        Precision of PowerTOSTmittyri 2017-12-09 21:05
        
        Precision of PowerTOST Astea 2017-12-10 00:10
        
        Precision of PowerTOST Helmut 2017-12-10 20:27
        
        Precision of PowerTOST Astea 2017-12-10 21:13
  - Reference-scaling: Don’t use FARTSSIE! pjs 2018-02-09 13:08
    - Reference-scaling: Don’t use FARTSSIE! Helmut 2018-02-09 20:15