Re: non-normality
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Re: non-normality

Dear Bart,

I have not analysed many binomial data sets with an animal model but my
suspicion is that when the mean incidence is outside 20-80 %, 
the variance components will be unreliable.  The fact that you
sometimes get a plausible answer does not prove the method works well.

If you get consistent answers with sire model, sire+dam and animal model
and maybe also on normal and binomial scale, then the data is
dominating the model. Otherwise, the model may dominate the data.

If others have some real experience, please lets hear it.


> X-Authentication-Warning: petidomo set sender 
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> From:
> Date: Mon, 17 Jul 2000 09:51:18 +0200
> Subject: non-normality
> To:
> MIME-version: 1.0
> Dear all,
> Continuing on Hermann's question about non-normal data, what is your opinion 
> on/ experience with using an animal model in analysing non-normal data? 
> I have applied it succesfully (i.e. convergence to reasonable estimates) on my 
> data. I tried to get a confirmation of the results from applying a sire + dam 
> model on the same data, but the iteration did not converge. This is very 
> likely caused by small family sizes in this particular case.
> I know that other users have bad experience with animal models, and they use 
> sire+dam models instead. 
> But first of all, it is not quite clear to me, if animal models applied to 
> discrete data lead to proper estimates?
> Best regards,
> Bart Ducro
> Animal Breeding & Genetics group
> Wageningen University
> The Netherlands
> --
> Asreml mailinglist archive:

Arthur Gilmour PhD        
Principal Research Scientist (Biometrics)            fax: <61> 2 6391 3899
NSW Agriculture                                           <61> 2 6391 3922
Orange Agricultural Institute             telephone work: <61> 2 6391 3815
Forest Rd, ORANGE, 2800, AUSTRALIA                  home: <61> 2 6362 0046

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