Bioequivalence and Bioavailability Forum • be careful with mixed models

be careful with mixed models [Regulatives / Guidelines]

posted by mittyri – Russia, 2017-05-02 19:53 (2548 d 16:41 ago) – Posting: # 17293
Views: 30,246

Hi Artem,

Welcome to the world of mixed modeling!
Helmut suggested (see endnote c) to switch to the model with all effects as fixed. Your model is the same as suggested by FDA (with Subject as random). So Phoenix switched to the mixed model and used Satterthwaite degrees of freedom (which could be not integer).
Note that it is impossible to provide ANOVA tables (partial/sequential ss output PHX-speaking) for mixed models.

So due to no convention in Russian brains you are free to use your current model or the model provided by Helmut (with all effects fixed). Latter is more suitable for me due to hazelnut brain.

PS: are there any incomplete data (missed period) for some subjects?

—
Kind regards,
Mittyri

Complete thread:

Russian «Экспертами» and their hobby Helmut 2017-04-29 00:46
- Low power of Group-by-Treatment interaction mittyri 2017-04-29 22:57
  - Let’s forget the Group-by-Treatment interaction, please! Helmut 2017-04-30 13:54
    - Let’s forget the Group-by-Treatment interaction, please! ElMaestro 2017-05-01 16:19
      - Some answers Helmut 2017-05-02 01:10
        
        Some answers ElMaestro 2017-05-02 09:04
        
        Example Helmut 2017-05-02 12:35
        
        Sensitivity of term? mittyri 2017-05-02 18:29
        
        Simulations Helmut 2017-05-05 14:38
        
        loosing specificity due to low sensitivity mittyri 2017-05-08 23:28
        
        loosing specificity due to low sensitivity Helmut 2017-05-09 00:55
        
        Loss in power Helmut 2017-05-06 17:31
        Interval between groups Helmut 2017-05-08 19:02
        
        IMP handling mittyri 2017-05-08 23:40
        
        IMP handling Helmut 2017-05-09 01:08
        
        Loss in power Helmut 2017-05-14 17:22
      - No convergence in JMP and Phoenix WinNonlin Helmut 2017-05-25 15:26
        
        Ouch?!??? ElMaestro 2017-05-25 16:24
- Russian «Экспертами» and their hobby Artem Gusev 2017-05-02 16:13
  - be careful with mixed modelsmittyri 2017-05-02 17:53
    - be careful with mixed models Artem Gusev 2017-05-03 11:02
  - p-value(s) in model 2 Helmut 2017-05-05 14:48
- Russian «Экспертами» following the EEU GLs Helmut 2017-05-24 20:17
  - Russian «Экспертами» following the EEU GLs Beholder 2017-05-24 22:37
    - Penalty for carelessness mittyri 2017-05-25 08:52
    - Russian «Экспертами» following the EEU GLs Beholder 2017-05-25 10:43
  - Russian «Экспертами» following the EEU GLs Mikalai 2018-01-04 10:43
    - Belarus = member of the EEU Helmut 2018-01-04 13:08
      - Belarus = member of the EEU Mikalai 2018-01-04 19:49
      - Trying your model for EEU mittyri 2018-01-04 22:04
        
        Trying your model for EEU Helmut 2018-01-05 00:06
        
        help us to stop it, please... Astea 2018-01-10 12:09
        
        help us to stop it, please... Beholder 2018-01-10 12:49
        regulators convinced by science? d_labes 2018-01-10 15:15
        
        regulators convinced by science? Beholder 2018-01-10 17:14
        
        Чёрт побери! d_labes 2018-01-10 18:53
        
        regulators convinced by science? Astea 2018-01-10 19:10
        
        Excuse me d_labes 2018-01-10 20:18
        
        Excuse me Astea 2018-01-10 20:38