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mcculloch
2008 Feb 10
2
[OT] good reference for mixed models and EM algorithm
Dear R People:
Sorry for the off-topic. Could someone recommend a good reference for
using the EM algorithm on mixed models, please?
I've been looking and there are so many of them. Perhaps someone here
can narrow things down a bit.
Thanks in advance,
Sincerely,
Erin
--
Erin Hodgess
Associate Professor
Department of Computer and Mathematical Sciences
University of Houston - Downtown
2004 Sep 21
1
lme RE variance computation
As I understand it lme (in R v1.9.x) estimates random effect variances
on a log scale, constraining them to be positive. Whilst this seems
sensible, it does lead to apparently biased estimates if the variance is
actually zero - which makes our simulation results look strange. Whilst
we need to think a bit deeper about it - I still haven't got my head
around what a negative variance could