Re: covAM

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
ORANGE NSW 2800
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

        To: ASREML-L_at_AGRIC.NSW.GOV.AU
        cc:
        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.

Julius

This message is intended for the addressee named and may contain
confidential information. If you are not the intended recipient or
received it in error, please delete the message and notify sender. Views
expressed are those of the individual sender and are not necessarily the
views of their organisation.
Received on Tue Dec 21 2004 - 17:10:37 EST