Bioequivalence and Bioavailability Forum • PowerTOST update

PowerTOST update [🇷 for BE/BA]

posted by d_labes – Berlin, Germany, 2016-02-01 20:16 (3799 d 21:30 ago) – Posting: # 15909
Views: 20,600

Dear Helmut,

❝ @Detlew: In my code I had to arbitrarily increase nstart in the second attempt, i.e., to

❝ x <- sampleN.RSABE(CV=CV[j], theta0=GMR[k], targetpower=0.9,


❝                    design="2x2x4", print=FALSE,

❝                    details=FALSE, nstart=x[["nlast"]]*1.5)

❝ because for CV=0.305, theta0=0.82 nlast is 442.

❝ With nstart=nlast the algo stops again (n 644, power 0.89243). Currently in line 159 of the source-code imax is fixed with 100. What do you think about introducing imax as an argument like in sampleN.TOST()?

your wish is my command.

Yes, I know that the starting values of the sample size search in such extreme settings as you are using here is not always good enough to come to a result. Introducing an argument imax makes for the functions sampleN.scABEL() or sampleN.RSABE() more sense than for sampleN.TOST() itself. For the latter the starting values are generally good enough to achieve the sample size within at max. 10 iterations or so. Usually a lower number is required.

The update will need some time. In the meantime I suggest to change your code to allow more then two tries to obtain a sample size from sampleN.scABEL() or sampleN.RSABE() if you need the functionality in the near future.
Sumefink like:

  ...

  x <- sampleN.RSABE(CV=CV[j], theta0=GMR[k],

                     design="2x2x4", print=FALSE,

                     details=FALSE)

  n <- x[["Sample size"]]]



  while (is.na(n){

    # 2nd try if necessary

    x <- sampleN.RSABE(CV=CV[j], theta0=GMR[k],

                       design="2x2x4", print=FALSE,

                       details=FALSE, nstart=x[["nlast"]])

    n <- x[["Sample size"]]]

  }

Maybe it would be a good idea to introduce additionally a counter in the while loop with reaching a maximum will break that loop.

—
Regards,

Detlew

Complete thread:

PowerTOST sample size FDA full replicate T/R ratio at 85% Shuanghe 2016-01-25 17:49
- PowerTOST sample size FDA full replicate T/R ratio at 85% d_labes 2016-01-26 12:05
  - PowerTOST sample size FDA full replicate T/R ratio at 85% Shuanghe 2016-01-26 12:55
    - PowerTOST sample size FDA full replicate T/R ratio at 85% d_labes 2016-01-26 14:07
    - maximum sample size at which CV? Helmut 2016-01-26 16:31
      - maximum sample size at which CV? nobody 2016-01-26 17:40
      - maximum sample size at which CV? d_labes 2016-01-27 08:41
        
        maximum sample size at which CV? nobody 2016-01-27 09:08
        
        OT: Stop - think -act d_labes 2016-01-27 09:31
      - maximum sample size at which CV? Shuanghe 2016-01-28 12:44
        
        target power 90% Helmut 2016-01-28 13:49
        
        PowerTOST updated_labes 2016-02-01 19:16
        
        #1,000 Helmut 2016-02-01 21:49
        
        OT: post #1,000 d_labes 2016-02-02 21:17
        #1,000 ElMaestro 2016-02-03 16:32
        
        #1,000 Helmut 2016-02-03 16:50
        OT: #1,000 d_labes 2016-02-05 15:50
        
        OT: #1,000 ElMaestro 2016-02-05 17:02
        
        OT: #1,000 d_labes 2016-02-05 19:48
        
        OT: #1,000 ElMaestro 2016-02-06 15:45
        
        OT: #1,000 nobody 2016-02-07 09:50