Bioequivalence and Bioavailability Forum • merciless tester!

merciless tester! [🇷 for BE/BA]

posted by Helmut – Vienna, Austria, 2016-03-07 19:56 (3391 d 21:59 ago) – Posting: # 16071
Views: 11,332

Hi Shuanghe,

❝ I noticed that at certain combinations PowerTOST would produce errors. e.g., with the following values

❝

❝ sampleN.scABEL(alpha = 0.05, targetpower = 0.8, theta0 = 0.91,


❝                     CV = 0.1, design = "2x2x4", regulator = "EMA")

❝ would produce error

❝ Error in if (pwr <= targetpower) cat(n, " ", formatC(pwr, digits = pd, :


❝   missing value where TRUE/FALSE needed

Confirmed.

❝ These error only appear when CV is extremely low so in practice it doesn't matter since no one will use 2x2x4 replicate study for product with ISCV of 10%.

Right.

❝ […] can anyone tell me what's going on here? Maybe it's apparent for R gurus but as R novice I have no idea what the message says.

At such a low CV you could use sampleN.TOST() to get a first idea:

library(PowerTOST)

x <- sampleN.TOST(targetpower = 0.8, theta0 = 0.91,

                  CV = 0.1, design = "2x2x4",

                  details = FALSE, print = FALSE)

cat(paste0("n = ", x[["Sample size"]], ", power = ",

           signif(x[["Achieved power"]], 6), "\n"))

n = 6, power = 0.913161

Looking at the source (type sampleN.scABEL in the console) we find

nmin <- 6

down <- FALSE

so I guess it could be possible. Needs some additional error-trapping. Detlew?

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Complete thread:

PowerTOST sample size EMA full replicate Shuanghe 2016-03-07 18:04
- merciless tester!Helmut 2016-03-07 18:56
- PowerTOST sample size EMA full replicate yjlee168 2016-03-07 20:15
- Merciless peer reviewers d_labes 2016-03-08 08:50
- PowerTOST V1.3-4 d_labes 2016-03-09 18:43
- PowerTOST sample size EMA full replicate Astea 2016-03-24 19:34
  - RSABE is not bijective (lengthy answer) Helmut 2016-03-25 14:23
    - RSABE is not bijective (lengthy answer) Astea 2016-03-27 21:07
      - ABEL sample size examples Helmut 2016-03-28 00:42
        
        ABEL sample size: more power! (joke) mittyri 2016-03-28 21:54