Re: covAM

From: Kevin Atkins <kevin.atkins_at_AGRIC.NSW.GOV.AU>
Date: Tue, 21 Dec 2004 17:10:37 +1100

Yes Julius, I agree with you and Arthur has suggested he will revise the
manual accordingly

K D Atkins
Principal Research Scientist
NSW Department of Primary Industries
OAI, Forest Road
ph: 02 6391 3816 fax: 02 6391 3922

Julius van der Werf <julius.vanderwerf_at_UNE.EDU.AU>
Sent by: ASReml users discussion group <ASREML-L_at_AGRIC.NSW.GOV.AU>
21/12/2004 03:56 PM
Please respond to ASReml users discussion group

        Subject: covAM

Dear Arthur et al

In the new ASReml manual on page 103 there is an example of a pin file
suggesting that the phenotypic variance is the sum of VA, VM and twice the
covariance between A and M (where A is additive genetic and M is maternal
genetic effect). However, the genetic covariance between direct and
maternal effects as expressed in one phenotype is always the result of A
and M coming from two different animals, with an additive genetic
relationship between them of 0.5.
So, the covariance between A and M in the same animal is 0.5*cov(A,M).
and var(P)=var(A+M+E)= VA + VM +2*0.5*cov(A,M) + VE
                = VA + VM + Cov(A,M) + VE

Therefore, if I'm correct, the appropriate coefficient in the pin file
should be one, not two.
I hope I am correct.


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Received on Tue Dec 21 2004 - 17:10:37 EST

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