Dear all,
W2k, R 2.5.1
I am trying out the AMMI function in the agricolae package, to analyse the
dependence of environment for a certain cultivar. The function responds to
four basic variables:
ENV Environment
GEN Genotype
REP Replication
Y Response
My question concerns the 'REP' term. When I normally do an analysis of
variance, the replication would refer to repeated observations within the
each field trial. In the case I am analysing right now, I have five years
of observations for each 'ENV', in such a case it feels natural to use
year as the most important replication of the environment- especially as I
am interested in long term trends. This approach also seems to work
allright.
But the field trials are also structured in three main blocks, subdivided
into five 'lattice' blocks, a structure that is powerful in the analysis
of variance. (I use a random call in lme{nlme}).
Is it possible to use the block structure also in the AMMI analysis? If
that is possible, how should I code? I have tried to find out in the
documentation, but if it is stated there I do not understand it.
Thank you
/CG
--
CG Pettersson, PhD
Swedish University of Agricultural Sciences (SLU)
Dept. of Crop Production Ecology. Box 7043.
SE-750 07 Uppsala, Sweden
cg.pettersson at vpe.slu.se
joris.dewolf at cropdesign.com
2007-Jul-24 07:35 UTC
[R] The 'REP' term in AMMI{agricolae}
The AMMI senso strictu part starts from the corrected data for genotype and
environment. In most cases where AMMI is applied (maybe also in the
agricolae package, I haven't checked), starts from the interaction effects
obtained through a general linear model anova.
It should be possible to replace the input by blups from your mixed model.
R news 7/1 (p14-19) gave some basic code for AMMI. There you should be able
to get ideas how to modify the code.
Joris
"CG Pettersson"
<cg.pettersson at vp
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[R] The 'REP' term in
23/07/2007 19:59 AMMI{agricolae}
Dear all,
W2k, R 2.5.1
I am trying out the AMMI function in the agricolae package, to analyse the
dependence of environment for a certain cultivar. The function responds to
four basic variables:
ENV Environment
GEN Genotype
REP Replication
Y Response
My question concerns the 'REP' term. When I normally do an analysis of
variance, the replication would refer to repeated observations within the
each field trial. In the case I am analysing right now, I have five years
of observations for each 'ENV', in such a case it feels natural to use
year as the most important replication of the environment- especially as I
am interested in long term trends. This approach also seems to work
allright.
But the field trials are also structured in three main blocks, subdivided
into five 'lattice' blocks, a structure that is powerful in the analysis
of variance. (I use a random call in lme{nlme}).
Is it possible to use the block structure also in the AMMI analysis? If
that is possible, how should I code? I have tried to find out in the
documentation, but if it is stated there I do not understand it.
Thank you
/CG
--
CG Pettersson, PhD
Swedish University of Agricultural Sciences (SLU)
Dept. of Crop Production Ecology. Box 7043.
SE-750 07 Uppsala, Sweden
cg.pettersson at vpe.slu.se
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