Bioequivalence and Bioavailability Forum • CVinter

CVinter > CVintra! [Power / Sample Size]

posted by Helmut – Vienna, Austria, 2007-10-15 18:15 (6827 d 23:49 ago) – Posting: # 1190
Views: 13,542

Dear stat_be!

❝ […] I have used proc glm for this and here MSE_Sub(seq) is less than MSE_residual so inter subject CV% can not be calculated. This is practical data obtained. […] Same thing happened in the data of Cmax where %CV_inter < %CV_intra.

It would be nice, if you could provide us with you C_max data!

Just a hint from Pharsight’s WinNonlin knowledge base:
Solution for WinNonlin Bioequivalence Warning 11094: Negative final variance component
The negative final Variance Component warning most likely indicates that, if using Subj(Seq) as a random effect, the within-subject variance (residual) is greater than the between-subject variance. Probably a more appropriate model is to move Subj(Seq) out of the random model and into the fixed model, i.e.,

Sequence+Subject(Sequence)+Formulation+Period.

To do this, use the following steps:

Start BE Wizard.
Specify reference formulation → Next
Specify dependent variable, e.g. Cmax → Next
Click Delete Random to remove Subject(Sequence) component → Back
Add Subject(Sequence) to the Fixed effects model as shown above
Click Calculate

You can reformulate you model in SAS accordingly.

—
Dif-tor heh smusma 🖖🏼 Довге життя Україна!
Helmut Schütz

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Complete thread:

can inter sub CV% > intra sub CV%? stat_be 2007-09-27 13:15 [Power / Sample Size]
- CVinter > CVintra! Helmut 2007-09-27 13:34
  - CVinter > CVintra! stat_be 2007-10-03 07:35
    - CVinter > CVintra! Ohlbe 2007-10-03 10:04
      - ANOVA not for Tmax! Helmut 2007-10-03 15:02
    - CVinter > CVintra!Helmut 2007-10-15 16:15
      - CVinter > CVintra! stat_be 2007-10-16 12:19
        
        CVinter > CVintra! Helmut 2007-10-16 13:15
      - CVinter > CVintra! krishna 2012-11-30 05:46
        
        WinNonlin random vs. fixed model Helmut 2012-11-30 13:54