[R] Log Cholesky parametrization in lme
spencer.graves at pdf.com
Mon Mar 20 17:59:06 CET 2006
Since you did not provide an example, I'm not sure I understand your
question. I will nevertheless offer some suggestions:
1. If you have not already, please review Pinheiro and Bates (2000)
Mixed-Effects Models in S and S-Plus (Springer).
2. Also, please review the existing methods for "lme" objects. The
following will produce a list:
Then "getAnywhere" would list the code. With this, you could make a
local copy under a different name and use "debug" to walk through the
code line by line to see what it does.
3. If this seems to produce more obfuscation than enlightenment for
you, please produce a simple, self-contained, reproducible example
describing what you want, including the R code for something that seemed
to come as close as anything you saw (as suggested in the posting guide!
Pryseley Assam wrote:
> Dear R-Users
> I used the nlme library to fit a linear mixed model (lme).
The random effect standard errors and correlation reported are
based on a Log-Cholesky parametrization. Can anyone tell me
how to get the Covariance matrix of the random effects, given
the above mentioned parameters based on the Log-Cholesky
> Thanks in advance
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