Dear Hermann,
Validity depends on the purpose of the analysis and the actual nature of the
data.
The variance components estimated by ASREML for non-normal data are not
strictly REML. They are the extrapolation of the REML method to non-normal
data and there has been a lot of concern that such extrapolation
does not always lead to 'correct' answers. Of course, we usually do
not know the correct answer (unless we have simulated the data).
So, I usually use several models and am more confident if the conclusions
(or interpretation) is not modified by the model.
Arthur
> X-Authentication-Warning: lamb.chiswick.anprod.csiro.au: petidomo set sender
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> Date: Thu, 13 Jul 2000 20:20:24 -0400
> From: "C. Balde" <cbalden@entelchile.net>
> MIME-Version: 1.0
> To: asreml <asreml@chiswick.anprod.csiro.au>
> Subject: Non normality
> Content-Transfer-Encoding: 7bit
>
> Dear Arthur,
>
> Just one question: How valid are the REML estimation of variance
> components when the data don't follow a normal distribution ?
>
> Hermann
>
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Arthur Gilmour PhD mailto:Arthur.Gilmour@agric.nsw.gov.au
Principal Research Scientist (Biometrics) fax: <61> 2 6391 3899
NSW Agriculture <61> 2 6391 3922
Orange Agricultural Institute telephone work: <61> 2 6391 3815
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While they watched, He was taken up,
and a cloud received Him out of their sight.
And while they looked steadfastly toward heaven as He went up,
behold two men stood by them in white apparel who also said
"Men of Galilee, why do you stand gazing up into heaven?
This same Jesus who was taken up from you into heaven,
will so come in like manner as you saw Him go into heaven."
Acts 1 9:11
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