Re: Functions of variance components

From: <arthur.gilmour_at_DPI.NSW.GOV.AU>
Date: Fri, 26 Oct 2007 11:06:35 +1000

Dear Rami,
Dear Arthur and ASReml Users
Is it possible to calculate an estimate of variance of geometric mean of
variance components with ASReml? Example: Variance of SQRT(X1 * X2) where
X1 and X2 are estimates of variance components. I looked at the chapter
about functions of variance components and could not find how to multiple
two components, is there a way around to do it?
Any suggestion, Could you please forward the message to the ASReml mailing
list as I am having problem when trying to post it there!
Rami Sawalha
Animal Breeding and Development
Scottish Agricultural College

1) You were not registered in the list with a name of 'Rami', 'Sawalha'
or 'sac' so if you are receiving messages from the list, it must be you
are registered under an old name without these words in it. Members
cannot email the list if the current email address differes from the
registered email address (typically you have moved and have old mail
forwarded or your mail system has been upgraded to send out addresses that
look different.
2) You can work out a variance of a function of variance components using
the expressions found in standard texts (e.g. I use Mood and Graybill
Intro to the Theory of Stats tihird edition page 180) However, I have
only programmed 3 particular expressions into ASReml - (Addition, ratio
and correlation) - being the main ones used. The variance of the variance
is returned in the .vvp file (not available under asreml-r and asreml-s)
so it should not be difficult to do the sums (but not in ASReml).

May Jesus Christ be gracious to you,

Arthur Gilmour, His servant .

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Received on Tue Oct 26 2007 - 11:06:35 EST

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