Bioequivalence and Bioavailability Forum • Must admit I am lost

Must admit I am lost [Regulatives / Guidelines]

posted by ElMaestro – Denmark, 2011-10-14 02:02 (4955 d 04:06 ago) – Posting: # 7489
Views: 13,777

Dear yicaoting,

impressive amount of work.
I must admit you lost me completely quite early here. The reason might be that I do not speak WNL or SAS and/or that my brain is walnut-sized.
My problem is I cannot see what you are trying to achieve.

For my learning purposes and/or your consideration:
1. Why would you use PROC MIXED when not specifying a random effect?
2. Do you know what the documented behaviour of PROC MIXED is when no random effect is specified? There is an example in the online manual but it does not tell what the general behaviour is.
3. Fitting a mixed model with just a lone sigma² on the diagnonal in the covariance matrix (=sigma²I) is conceptually similar to the linear model, the difference being just that missing values does not mean discarded subjects with PROC MIXED.
4. What is the documented behaviour of PROC MIXED when you specify the same effect as both random and fixed? If I get you right in this case [subject(sequence)] it just defaulted to sigma² on the diagonal in the covariance matrix, but would anyone really specify a mixed model that way? I speculate, the inner works might simply skip the (or better: a) random effect if it has been already specified as fixed, which in your case just leads to pt. 2. above. If it does exactly the opposite (skips the fixed effect when it is specified as random) it would lead to the same.

—
Pass or fail!
ElMaestro

Complete thread:

Least Square Means (LSM) for unequal sequence yicaoting 2011-10-03 14:37 [Regulatives / Guidelines]
- Least Square Means (LSM) for unequal sequence ElMaestro 2011-10-03 14:51
  - Least Square Means (LSM) for unequal sequence yicaoting 2011-10-03 15:28
    - Least Square Means (LSM) for unequal sequence ElMaestro 2011-10-03 15:36
    - Least Square Means (LSM) for unequal sequence Helmut 2011-10-03 16:14
      - Least Square Means (LSM) for unequal sequence ElMaestro 2011-10-03 20:10
  - Least Square Means (LSM) for unequal sequence Pankaj Bhangale 2011-10-04 14:52
    - Weighted Means? Helmut 2011-10-05 01:53
- LSM for unbalanced sequences -SAS- d_labes 2011-10-04 09:39
  - LSM for unbalanced sequences -SAS- yicaoting 2011-10-04 19:37
    - SE for unbalanced sequences SAS vs. WinNonlin Helmut 2011-10-05 01:01
    - LS Means mean? d_labes 2011-10-05 12:45
      - LS Means mean? ElMaestro 2011-10-05 13:23
      - PHX/WNL vs. SAS Helmut 2011-10-08 02:21
        
        PHX/WNL vs. SAS Proc Mixed d_labes 2011-10-10 15:46
        
        PHX/WNL vs. SAS Proc Mixed Helmut 2011-10-10 16:30
        
        PHX/WNL vs. SAS Proc Mixed ElMaestro 2011-10-10 19:53
        
        Real mixed effects in WNL, SAS, GLM or Mixed (1) yicaoting 2011-10-13 18:39
        Real mixed effects in WNL, SAS, GLM or Mixed (2) yicaoting 2011-10-13 18:52
        Real mixed effects in WNL, SAS, GLM or Mixed (3) yicaoting 2011-10-13 19:05
        
        Must admit I am lostElMaestro 2011-10-14 00:02
        
        Must admit I am lost yicaoting 2011-10-14 06:30
        
        Must admit I am lost - edited ElMaestro 2011-10-14 13:23