Have you considered the 'nlme' package, well documented in Pinheiro
and Bates (2000) Mixed-Effects Models in S and S-Plus (Springer)?
Hope this helps.
Spencer Graves
souvik banerjee wrote:> Hi
> Is there any way to fit a bivaraite longitudinal mixed model using R. I
have
> a data set with col names
>
> resp1 (Y_ij1), resp2 (Y_ij2), timepts (t_ij), unit(i)
>
> j=1,2,..,m and i=1,2,..n.
>
> I want to fit the following two models
>
> Model 1
>
> Y_ij1, Y_ij2 | U_i = u_i ~ N(alpha + u_i + beta1*t_ij, Sigma)
> U_i ~ iid N(0, sigu^2)
>
> Sigma = bivariate AR structure
>
> alpha and beta are vectors of order 2.
>
> Model 2
> Y_ij, Y_ij2 | U_i = u_i ~ N(alpha + u_i + beta1*t_ij + U_i2*t_ij, Sigma)
>
> U_i=(U_i1,U_i2) ~ iid N(0, Omega)
>
> Sigma =bivariate AR structure
>
> Here alpha and beta are vectors of order 2.
>
> Moreover can we assume a structure for Omega.
>
> Any help is greatly appreciated.
> Souvik Banerjee
> Junior Research Fellow
> Dept of Statistics
> University of calcutta
>
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>
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