[R] Mixed Models providing a correlation structure.
mresende at ufl.edu
Wed Jul 11 16:27:21 CEST 2012
Thanks for the quick reply.
Unfortunately I don't have access to Pinheiro and Bates. I tried googling
the pdSymm and lme but I still cannot get the syntax right.
In my model, I only have 1 random factor with repetitions (groups) (e.g. 2
records per each level)
I am pasting bellow a very small example (2 records and 2 levels) which
demonstrates the error I am having.
The syntax of lme is obviously wrong, and any help would be appreciated:
> CovM <- matrix(c(1,0.5,0.5,1),2)
[1,] 1.0 0.5
[2,] 0.5 1.0
> DATA <- data.frame(Y = c(rnorm(4)), Random = c(1,1,2,2))
1 0.24037680 1
2 0.03477704 1
3 -1.83389279 2
4 -0.84793117 2
> lme(Y~Random, data = DATA, random = list(Random = pdSymm
Error in `Names<-.pdMat`(`*tmp*`, value = c("(Intercept)", "Random")) :
Length of names should be 1
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