[R] What is wrong with this contrast matrix?
Christoph Scherber
Christoph.Scherber at agr.uni-goettingen.de
Thu Jul 24 17:30:57 CEST 2008
Dear all,
I am fitting a multivariate linear model with 7 response variables and 1 explanatory variable.
The following matrix P:
P <- cbind(
c(1,-1,0,0,0,0,0),
c(2,2,2,2,2,-5,-5),
c(1,0,0,-1,0,0,0),
c(-2,-2,0,-2,2,2,2),
c(-2,1,0,1,0,0,0),
c(0,-1,0,1,0,0,0))
should consist of orthogonal elements (as can be shown using %*% on the individual columns).
However, when I use
linhyp=linear.hypothesis(model, "explanatory.variable", P=P)
I get an error saying
Error in linear.hypothesis.mlm(mult1, "logdiv", P = P) :
The error SSP matrix is apparently of deficient rank = 4 < 6
Which I interpret as there are too many non-zero rows in the matrix, P.
Is that correct? And how can I assess if the matrix is orthogonal (given that it is non-symmetrical,
hence det(P) and other matrix operations won?t work)
Many thanks for your help!
Best wishes
Christoph.
(using R 2.7.1 on Windows XP)
--
Dr. rer.nat. Christoph Scherber
University of Goettingen
DNPW, Agroecology
Waldweg 26
D-37073 Goettingen
Germany
phone +49 (0)551 39 8807
fax +49 (0)551 39 8806
Homepage http://www.gwdg.de/~cscherb1
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