Bioequivalence and Bioavailability Forum • All models are wrong…

All models are wrong… [Software]

posted by Helmut – Vienna, Austria, 2014-02-02 03:31 (4524 d 12:31 ago) – Posting: # 12312
Views: 32,679

Hi ElMaestro,

❝ Actually, I am inclined to think there is something wrong with that subtraction in the first place.

I told you on the phone that I’m going to meet Martin. He said: “Maybe the model is wrong.” Fuck. In Chow/Liu Chapter 7.3.1 (p192 last edition) I read:

A negative estimate may indicate that model 3.1.1 is incorrect or sample size is too small. More details on negative estimates in analysis of variance components can be found in Hocking (1985).

My emphasis. 3.1.1 is the usual 2,2,2 (though with carry over).
So if this model is wrong, which one is correct? :confused:

I’m not sure whether I shall invest in a book I likely will not understand anyway.

—
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Helmut Schütz

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Complete thread:

How to calculate intersubject variability in PHX WinNonlin zan 2014-01-29 23:58
- Negative variance component Helmut 2014-01-30 01:16
  - Negative variance component zan 2014-01-30 18:11
  - Negative variance component zan 2014-01-31 00:16
    - Negative variance component ElMaestro 2014-01-31 08:20
    - Negative variance component yjlee168 2014-01-31 10:26
      - Example data set Helmut 2014-02-01 16:03
        
        Example data set yjlee168 2014-02-01 17:40
        
        PHX build 6.3.0.395 / 6.4.0.511 Helmut 2014-02-02 02:04
        
        PHX build 6.3.0.395 / 6.4.0.511 yjlee168 2014-02-02 07:54
    - Negative variance component ElMaestro 2014-02-01 16:31
      - Negative variance component yjlee168 2014-02-01 17:47
        
        Just thinking loud ElMaestro 2014-02-01 19:02
        
        All models are wrong…Helmut 2014-02-02 02:31
        
        another book for linear model yjlee168 2014-02-02 08:07
      - References Helmut 2014-02-02 02:19
        
        References ElMaestro 2014-02-02 09:56
    - Negative variance component – Chow/Liu d_labes 2014-02-03 09:02
      - Negative variance component – Chow/Liu ElMaestro 2014-02-03 10:22
        
        Variance components – Proc mixed d_labes 2014-02-03 11:58
        
        Variance components – Proc mixed ElMaestro 2014-02-03 12:58
        
        Variance components – Proc mixed 90% CIs d_labes 2014-02-03 13:16
        Variance components – Proc mixed Helmut 2014-02-03 14:14
        
        FDA code for non-replicate crossover? d_labes 2014-02-03 15:54
        
        Proc GLM rulez Helmut 2014-02-03 16:16
        
        Variance components – Proc mixed yjlee168 2014-02-03 20:43
        
        NOBOUND Helmut 2014-02-03 22:08
      - lm() or lme() for 2x2x2 study design? yjlee168 2014-02-03 20:22
        
        lm() or lme() for 2x2x2 study design? ElMaestro 2014-02-03 22:11
        
        lm() or lme() for 2x2x2 study design? yjlee168 2014-02-04 13:09
        
        bear for 2x2x2 study with negative variance components yjlee168 2014-02-05 19:12