Message-ID: <loom.20060715T104818-562@post.gmane.org>
Date: 2006-07-15T08:50:26Z
From: Dieter Menne
Subject: Questions about extract-lme.cov
Li, Hua <HUL <at> stowers-institute.org> writes:
> I am using extract.lme.cov to extract the covariance matrix of lme. But
> the results are not expected.
>
> b <- lme(travel~1,Rail,~1|Rail)
>
> The default correlation for lme is no correlation within groups.
>
> >extract.lme.cov(b,Rail)
>
> The part of covariance matrix looks like:
>
> 1 2 3 4 5 6
> 1 631.4778 615.3111 615.3111 0.0000 0.0000 0.0000
> 2 615.3111 631.4778 615.3111 0.0000 0.0000 0.0000
> 3 615.3111 615.3111 631.4778 0.0000 0.0000 0.0000
> 4 0.0000 0.0000 0.0000 631.4778 615.3111 615.3111
> 5 0.0000 0.0000 0.0000 615.3111 631.4778 615.3111
> 6 0.0000 0.0000 0.0000 615.3111 615.3111 631.4778
>
> Where does the covariance come from? Maybe I'm missing sth here?
Maybe
VarCorr(b)
gives all you need, because
extract.lme.cov2(b,Rail,start.level=2)
or even
extract.lme.cov(b,Rail,start.level=2)
are a bit redundant.
Dieter