Bioequivalence and Bioavailability Forum • Sample size justification

Sample size justification [Design Issues]

posted by Helmut – Vienna, Austria, 2015-08-07 03:21 (3563 d 03:26 ago) – Posting: # 15189
Views: 12,105

Hi Balaga,

❝ "what is the maximum expected sample size (for two way crossover design) with the intra subject coefficient of variation of pilot study data around 15%.

It depends. ;-)

❝ I have the following data,

❝ Observed Pilot study ISCV% - 12.29%

Sample size of the pilot?

❝ With the observed pilot study (two way crossover design) ISCV 12.29%, is it possible to expect the 15% ISCV or not for pivotal study design?

Yes. Once you’ll tell us the sample size of the pilot maybe more about it…

❝ What should be the null ratio considerate for the same and under what circumstances we should go for widening of the null ration beyond the 95 - 105% limits or we can in all cases?

If you are not dealing with a HVD/HVDP and the GMR in the pilot was within this range, fine. Otherwise expecting a larger deviation is not a bad idea.

❝ During sample size calculation, is there is any restriction to expect the null test/reference ratios in between 95.00 to 105.00% only? I wont feel so.

Correct. BTW, power curves are symmetric around 0 in the log-domain. Therefore, you get the same power at 95% and at 1/95% ~105.26% (log ±0.051293). If you expect a 5% deviation of T from R (and are not sure about the direction), always estimate the sample size at 95%.

❝ […] if there is any separate link to access the Diletti et. al. (1991) sample size calculation article.?

Check your [image]

.
IMHO, Diletti’s “Table 1” is of historic interest only (too wide step sizes).

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Complete thread:

Sample size justification bkrao 2015-08-06 09:12 [Design Issues]
- Sample size justification BE-proff 2015-08-06 14:19
  - PASS simulator? d_labes 2015-08-06 15:25
    - PASS simulator? BE-proff 2015-08-07 20:08
      - Owen’s Q | noncentral t | shifted central t Helmut 2015-08-08 02:32
        
        Owen’s Q | noncentral t | shifted central t BE-proff 2015-08-09 15:36
        
        PowerTOST crash-course Helmut 2015-08-09 16:40
        
        Owen’s Q | noncentral t | shifted central t - PASS? d_labes 2015-08-10 11:30
- Sample size justificationHelmut 2015-08-07 01:21
  - Sample size justification bkrao 2015-08-07 06:06
    - Guesstimates Helmut 2015-08-07 13:53
      - Guesstimates bkrao 2015-08-08 06:03
        
        Guesstimates jag009 2015-08-10 20:08
        
        Guesstimates bkrao 2015-08-10 20:44