Bioequivalence and Bioavailability Forum • inter- / intra- / total variance

inter- / intra- / total variance [Software]

posted by Helmut – Vienna, Austria, 2009-10-01 15:52 (5679 d 09:51 ago) – Posting: # 4285
Views: 27,532

Dear Yuvraj!

❝ […] but when we have information about Point Estimate, Intersubject variability and Power then how to calculate sample size?

Is it possible that you are mixing up terms (see this post)? If you have data from a parallel study, you have the total (or pooled) variance. You may split the total variance into inter- (between) and intra- (within) subject variance only in a cross-over study. So there are some possibilities:

You mixed up terms (have the total variability) and want to plan another parallel study. Fine, you may use software or approximations.
You have total variability from a parallel design and want to plan a cross-over. No way. OK, you may do that, but most likely much too many subjects will be included. That’s not ethical.
You have inter-subject from a cross-over. Just look up the report for intra.

I’m not sure what you mean by:

❝ we have information about […] Power

You set power to an arbitrary value in sample size estimation. Power = 1–β, where β (or error type II) is the producer’s risk of missing demonstration of BE in a given study for a product which actually is bioequivalent. This risk is generally set to 10–20% (power 80–90%).

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Complete thread:

Sample Size Calculation sasikumar 2008-04-03 09:19 [Software]
- Sample Size Calculation (SAS) Jaime_R 2008-04-03 13:13
- Sample Size Calculation d_labes 2008-04-23 11:54
  - Sample Size Calculation balakotu 2009-09-07 07:51
  - Sample Size Calculation yuvrajkatkar 2009-09-19 09:24
    - Paper, pencil, brain ;-) Helmut 2009-09-19 11:48
      - Paper, pencil, brain ;-) yuvrajkatkar 2009-09-21 15:10
        
        Paper, pencil, brain ;-) Helmut 2009-09-21 15:23
        Paper, pencil, brain ;-) Helmut 2009-09-21 18:33
        
        Paper, pencil, brain ;-) yuvrajkatkar 2009-09-22 16:09
        
        No paper, pencil, brain :-( Helmut 2009-09-22 18:22
        
        about your lectures yuvrajkatkar 2009-09-23 07:27
        
        About Trust Helmut 2009-09-23 13:50
        
        sample size calculation yuvrajkatkar 2009-10-01 13:33
        
        inter- / intra- / total varianceHelmut 2009-10-01 13:52
        
        inter- / intra- / total variance yuvrajkatkar 2009-10-01 17:13
        
        Theta?! Helmut 2009-10-01 17:30
        
        sample size for parallel design yuvrajkatkar 2009-10-03 07:44
        
        Reference? Helmut 2009-10-03 13:46
        
        MSE obtain from Parallel study in WinNonlin yuvrajkatkar 2009-10-09 16:46
        
        Parallel study in WinNonlin Helmut 2009-10-10 10:51