Re: how to fit a G struture

From: <arthur.gilmour_at_DPI.NSW.GOV.AU>
Date: Tue, 24 Apr 2007 13:34:47 +1000

Dear Felicity,
Can someone please suggest to me how to fit a G structure to the following
parental model over trials? I have:

ccs ~ mu Trial at(Trial,1).lin(Plot) at(Trial,3).lin(Nrow),
      !f mv !r at(Trial,2).Rep,
      Female and(Male) Trial.Female -Trial.Male and(Trial.Male)
4 2 1
12 Plot AR .1
41 Nrow AR .38
12 Plot AR .1
41 Nrow AR .38
12 Plot AR .12
10 Nrow AR .16
12 Plot AR .1
13 Nrow AR .38
Trial.Female 2
4 0 CORUH !+5
Female 0 ID

This runs but I would like the G structure over the combined Trial.Female
-Trial.Male and(Trial.Male).

First note that Female and(Male) assumes Female and Male are coded
so that Female_i is the same plant as Male_i for all i.

It means that the design matrix for Male is added to the design matrix to
so in the output there will only be one set of effects, labelled Female.

Similarly Trial.Female -Trial.Male and(Trial.Male) results in one set of
effects labelled in the output Trial.Female

2) The above model is a little unusual.
It is not common the fit the 'Female' variance component when you put a
structure on Trail.Female

The Female term fits a common covariance accross Trials. The structure
fits a common
correlation (differing variances) . It is more usual to drop the Female
component when you fit a covariance
structure to the interaction term.

I trust this helps.

May you know Jesus Christ and His blessing in 2007,

Arthur Gilmour, His servant .

Mixed model regression mapping for QTL detection in experimental crosses.
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Received on Sat Apr 24 2007 - 13:34:47 EST

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