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

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

posted by ElMaestro – Denmark, 2013-08-14 16:25 (4291 d 05:04 ago) – Posting: # 11286
Views: 10,154

Dear d_labes,

❝ 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.

Thank you.
Yes, I realise that the error variance in TRT and RTR can differ but does that leave us really helpless? From the two sequences we get two equations with two unknowns -eqn. 9.3.21- from which we can solve explicitly for s²_wR and s²_wT. We could plug those into 9.2.17 and get 90% CI's.
Am I overlooking something?

—
Pass or fail!
ElMaestro

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