[R-sig-ME] meaning of lmer formula
don-r-help at isis.cs3-inc.com
Wed Sep 6 23:17:14 CEST 2017
Ben Bolker writes:
> > Does (input1 + input2 | group) mean the same as
> > (input1 | group) + (input2 | group) or does it also include a
> > correlation between input1 and input2 ?
> The latter.
It occurred to me after I wrote the questions that
(input1 | group) + (input2 | group) might also include that
correlation between input1 and input2 - I gather now it does not.
> > Back to my question about additive shifts, is that extra correlation
> > required in order to maintain invariance over additive shifts?
One more question (so far):
If there are two different groupings, would
(input1 + input2 | group1) + (input1 + input2 | group2)
involve correlations between group1 and group2 ?
If I think of (1+input1 | group) as a 2x2 matrix, and
(1+input1+input2 | group) as 3x3
then is (1+input1+input2 | group1)+(1+input1+input2 | group2)
two independent 3x3's or a full 6x6 (or something else) ?
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