Bioequivalence and Bioavailability Forum • CVinter

CVinter > CVintra! [Power / Sample Size]

posted by Helmut – Vienna, Austria, 2007-09-27 15:34 (6424 d 07:11 ago) – Posting: # 1139
Views: 11,135

Dear stat_be!

❝ […] my doubts related to inter subject CV% and intra subject CV%.

So you are talking about a cross-over design.

❝ 1. Can inter subject CV% greater than intra subject CV? if yes then in what situation it may happen and what conclusion can be drawn on that basis?

Yes, this is the rule. In a cross-over design the PK responses within a particular subject are compared (between occasions).
I hardly can imagine a situation where variability between subjects (i.e., Brown vs Blair) is lower than within a subject (i.e., Brown on day 1 vs Brown on day 2). Although theoretical possible from a statistical point of view, such a behaviour is counterintuitive, and IMHO not a single case is described in the literature.
BTW, the expectation of CV_intra < CV_inter leads to the general preference of cross-over designs over parallel designs in BE studies.

❝ 2. what are the formulas to calculate to both of them from GLM Anova?

For formulas see this post.

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Complete thread:

can inter sub CV% > intra sub CV%? stat_be 2007-09-27 13:15
- 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