[R-sig-ME] [R] understanding I() in lmer formula
Don Cohen
don-r-help at isis.cs3-inc.com
Sat Jun 17 20:59:15 CEST 2017
> > vignette("lmer",package="lme4")
> > gives me
> > Warning message:
> > vignette 'lmer' not found
>
> That's surprising ... what's packageVersion("lme4") ?
> packageVersion("lme4")
[1] '1.1.14'
[actually I'm replacing left and right non-ascii quotes above]
> Pinheiro and Bates (2000),
I'll look, but it seems that for something that old, even if it does
contain these details, they are likely to be out of date.
I noticed http://lme4.r-forge.r-project.org/lMMwR/lrgprt.pdf
which is from 2010 says on p.15
The vector u is available in fm01ML at re. The vector Beta and the model matrix
X are in fm01ML at fe.
and this seems no longer true - I get
Error: no slot of name "fe" for this object of class "lmerMod"
> Yes. (So in particular this model are 3*(3+1)/2=6 parameters
> (equivalent to s^2{1}, s^2(x),s^2(y), cov(1,x), cov(1,y), cov(x,y))
That might explain why changing (x+y+z+u+v+w||g) to single | seems to
run a lot longer (I interrupted it so I don't know how much longer).
Do you have an estimate of how number of terms affects run time?
If a paper describes various things being used as random effects
would you assume | or || ?
Perhaps it depends on the number of effects? The example I sent
contained quite a few, and the original from which that was extracted
contained over a dozen.
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