Bioequivalence and Bioavailability Forum

R-package randomizeBE [Regulatives / Guidelines]

posted by d_labes  – Berlin, Germany, 2012-07-06 11:54 (5092 d 21:19 ago) – Posting: # 8899
Views: 14,820

Dear All!

❝ ❝ Random freaks may use varying block sizes chosen at random.

❝

❝ Too stupid to code that…

We proudly present on CRAN now :

A little (futile) randomizer for BE studies
R-package randomizeBE

Features:

• Also free (think 'free' not like 'free beer' but 'free in speech')
  like this one of ElMaestro's alter ego and open source
  
• not restricted to 2x2 crossover
  
• block randomization
  
• randomly chosen block sizes from a list of block sizes
  
• control of randomness via Wald-Wolfowitz runs test (may be switched off)
  

Here some simulation results concerning probability of obtaining 'alternating' random lists in 2x2 crossover (randomness control switched off):
1 000 000 simulations, alpha=0.05 for the runs test

                     runs test
subjects blocksize  %significant  %alternating
----------------------------------------------
12         0 (12)       2.62          0.206
           6            3.54          0.515
           4            5.57          0.928
           2 4          9.47          1.576    randomly chosen block sizes
----------------------------------------------
24         0 (24)       5.95         <0.0001
          12            6.28          0.0001
           4           19.33          0.0039
           4 6         14.90          0.0023   randomly chosen block sizes
----------------------------------------------

Lessons learned:

• If sample size not too low and block size also the probability to 'randomize' an alternating list is vanishing small.
  
• The randomness control via runs test with significance level alpha=0.05 is much to stringent (much more lists were considered non random than our alternates).
  
• The question to control/not control the randomness of the random list should not concern us much.
  IMHO we are throwing a spanner in the works of chance if we do it too serious.

BTW: Helmut how did you act on the deficiency letter 20+ years ago? Could you convince them that dicing 6 times in series 6 pips (or six times 1 pips) although has low probability is possible?

---

Edit: Package linked. [Helmut]

Complete thread:

• USFDA requirement for randomization Ravi 2012-06-15 13:39 [Regulatives / Guidelines] 
  • randomization: validation Helmut 2012-06-15 17:39
    • randomization: runs test? validation? d_labes 2012-06-16 13:10
      • randomization: runs test? validation? Helmut 2012-06-16 14:00
        • probability nearly zero? d_labes 2012-06-16 16:11
          • probability nearly zero! Helmut 2012-06-16 17:08
            • R-package randomizeBEd_labes 2012-07-06 09:54
              • R-package randomizeBE Helmut 2012-07-06 12:51
    • randomization: validation ElMaestro 2012-06-16 13:31
      • randomization: runs test Helmut 2012-06-16 14:42
        • randomization: runs test ElMaestro 2012-06-16 14:48
          • randomization: runs test Helmut 2012-06-16 15:10
        • very cool coding style ElMaestro 2012-06-16 19:12
          • Better a good steal than a bad reinvention Helmut 2012-06-17 13:22
            • Better a good steal than a bad reinvention ElMaestro 2012-06-17 19:58
              • Sorry! Helmut 2012-06-18 13:26
                • Sorry! ElMaestro 2012-06-18 15:19
          • Dancing with the dice d_labes 2012-06-18 15:38
            • Silly's randomization 2x2 xover d_labes 2012-06-18 16:30
              • Silly's randomization 2x2 xover Helmut 2012-06-18 17:14
            • Clumsy code Helmut 2012-06-18 17:42
              • Clumsy code ElMaestro 2012-06-18 18:01
                • Speed kills Helmut 2012-06-18 18:56
                  • Speed kills jag009 2012-09-17 21:46