Bioequivalence and Bioavailability Forum • TRT|RTR rulez? Really? No.

TRT|RTR rulez? Really? No. [RSABE / ABEL]

posted by d_labes – Berlin, Germany, 2013-08-14 15:34 (4291 d 03:59 ago) – Posting: # 11284
Views: 10,110

Dear Öberster größter Meister,

❝ ❝ Read chapter 9.3 of Chow and Liu, especially 9.3.4 "Assessment of Intra-Subject Variabilities". And if you have, read it again.

❝ ...

❝ I don't really get all the points of C&L. If any :-D

Did you follow my advice? Read again? If yes, read again. If no, don't worry longer about that issue :-D

❝ ❝ (...) there is no valid way to evaluate T versus R in case of heteroscedasticity. And this renders the advantage useless.

❝

❝ Can you explain me why in words that are adapted to people with walnut-sized brains such as myself?

An initiated must speak in words that are not understandable by ordinary people, not to mention people with walnut-sized brains :cool:

.
The key is hidden in Formulas 9.3.21 and 9.3.22 showing that the expected variances of the sequence groups TRT and RTR are not the same. Thus you can't pool them without the danger of too liberal or too conservative results after doing so. You had to use a method which accounts for this heteroscedasticity. AFAIK there is no in the context we discuss here, except eventually a real mixed model analysis.

—
Regards,

Detlew

Complete thread:

3-per, 2-trt designs and estimation of intra-subj. variance ElMaestro 2013-08-12 19:54
- 3-per, 2-trt designs and estimation of intra-subj. variance Dr_Dan 2013-08-13 10:11
  - 3-per, 2-trt designs and estimation of intra-subj. variance ElMaestro 2013-08-13 15:00
    - TRT|RTR rulez! Helmut 2013-08-13 18:23
      - TRT|RTR rulez? Really? d_labes 2013-08-14 08:16
        
        TRT|RTR rulez? Really? Yes. ElMaestro 2013-08-14 11:29
        
        TRT|RTR rulez? Really? No.d_labes 2013-08-14 13:34
        
        TRT|RTR rulez? Really? No. ElMaestro 2013-08-14 14:25
        
        TRT|RTR Lost in formulas. d_labes 2013-08-14 16:35
        
        TRT|RTR rulez? References Helmut 2013-08-14 13:44
        
        References László & László d_labes 2013-08-14 19:12
        
        Heteroscedasticity Helmut 2013-08-17 17:33
        
        Heteroscedasticity: TRT|RTR rulez! d_labes 2013-08-29 16:45
        
        Heteroscedasticity: TRT|RTR rulez! ElMaestro 2013-08-29 17:50
        
        Sims & evaluation d_labes 2013-08-30 09:16
        
        Sims & evaluation ElMaestro 2013-08-31 14:11
        
        Evaluation subtleties d_labes 2013-08-31 17:20