[R-sig-ME] specifying independence of random effects?
r.j.forsyth at newcastle.ac.uk
Thu Dec 10 17:31:21 CET 2009
I'm trying to specify a mixed-effect model describing "unmet NEED" (of
families with disabled children) as a function of IMPAIRMENT (i.e.
intrinsic severity of the child's condition) and AREA of residence
(factor with ~15 levels). The impairment measure is a unidimensional
variable but it needs "calibrating" for separate types of disability
(autism, cerebral palsy etc) represented by another factor, DISCAT
In lmer syntax I have
NEED ~ IMPAIRMENT | DISCAT + 1 | AREA
but I want to specify independence of random effects. I'm aware of the
pdDiag options in the nlme library but unsure how to specify the model
in lme syntax?
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