Re: repeated measures models

# Re: repeated measures models

>
> Arthur wrote:-
>
> <snip>
> >
> >  intake1 intake2 intake3 other ~ Trait Tr.line Tr.feedflock Tr.damage,
> >  Tr.brtype Tr.sex !r Tr.sire
> >
> > 1 2 0
> > 1728   #no. of animals in the data
> > Tr 0 US  E11 E12 E22 E31 E32 E33 E41 E42 E43 E44  !=1212213330
> >
> > Tr.sire 2
> > Tr 0 US  G11 G12 G22 G31 G32 G33 G41 G42 G43 G44  !=4545546660
> > sire
> >
> >SO what we have here is setting the model up as standard multivariate
> >and then constraining the intake variances and covariances.
> >
> >You could of course fit it with unconstrained variances.
> >
> >The way the first model was fitted, the 'units' term gave the E12 E32 R32
> >covariances and the  'units + residual' gave the E11, E22 and E33 terms.
> >
> >The sire term gave G11=G21=G22=G31=G32=G33
> >
> >When you get this running, you may see how to extend to more complex models.
>

Ron wrote

> Okay, I can see how that might work.
>
> But for a repeatability model, you need to have the
> genetic correlation equal to one among the 3 intake
> traits. I don't see how you do this, I know it
> uses the and() function in some way, but I don't understand it.
>
> Ron.

Arthur replies:
I'm not convinced you need to have a genetic correlation of 1 but
if you do, and want to fit the model, the way would be to fit
an equivalent model:

...      !r sire Tr|4/sire ...

sire 2
2 0 US S11 S21 S22
sire

Under this model, the genetic variance for intake  is S11
for other   is S11 + S22
covariance is             S11+S21  \

For computational ease, you might like to scale the  unrepeated trait
so that its sire variance is greater than the sire variance for intake
[so that S22 has a positive value]

Arthur
>

<><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><>
Arthur Gilmour PhD                    email: Arthur.Gilmour@agric.nsw.gov.au
Senior Research Scientist (Biometrics)                 fax: <61> 2 6391 3899
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