Bivariate random regressions

From: M R Robinson <matthew.r.robinson_at_ED.AC.UK>
Date: Fri, 23 Feb 2007 11:57:26 +0000


I wish to run a bivariate animal model and then build this up into a
bivariate random regression and I was hoping for some help.

I want to model how two traits covary firstly phenotypically and then
dividing phenotypic variance into additive and residual components.

So as an example I can run random regressions each trait in this way:

ANIMAL !P # pedigree factor, refers to pedigree file
INC # horn increment growth in sheep
AGE !A # age as a factor in years 1-5
sAGE !A # standardized age (-1 to 1)
CYR !A # year of measurement to control for
                         # environmental effects during the year of growth
WEIGHT # weight of the sheep measured in

Sheep1.ped !ALPHA !MAKE !SKIP 1
incNHMalesrr.asd !SKIP 1 !DOPART 1 !MAXIT 100


INC ~ mu AGE CYR !f mv

1 2 0 !STEP 0.01


!PVAL sAGE -1 -0.5 0 0.5 1

INC ~ mu AGE CYR !r leg(sAGE,2).ANIMAL !f mv

1 2 1 !STEP 0.01


leg(sAGE,2).ANIMAL 2
leg(sAGE,2) 0 US
0 0.1
0 0 0.1

The first part gives me phenotypic correlations and covariances for
horn growth and the second part then breaks this down into additive and
residual components using a second order polynomial.

I know the methodology for running a bivariate model:


INC WEIGHT ~ Trait Trait.AGE !r Trait.ANIMAL

1 2 1

Trait 0 US

Trait.ANIMAL 2
Trait 0 US

However I have no idea how to merge the analysis methods and seperate
both the variances and covariances into the five age groups which I
have. This would be important to me as I want to look at how early
investment in in weight and horn growth affect later trait development
and whether there's any evidence of changing phenotypic, and genetic
correlations with age.

Any help would be greatly appreciated and I thank-you very much for your time.

King regards,

Matt Robinson
Institute of Evolutionary Biology
University of Edinburgh
Received on Tue Feb 23 2007 - 11:57:26 EST

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