[R-sig-ME] Why || doesn't zero out the correlations in lmer
me @end|ng |rom ph||||p@|d@y@com
Fri Oct 8 23:46:24 CEST 2021
This is a well-documented issue: || doesn't zero correlations between a
categorical variable's levels. As far as I know, there are
software-development/technical reasons for this, not statistical ones.
The afex package has an implementation that zeroes everything out.
On 8/10/21 4:32 pm, Simon Harmel wrote:
> Dear Colleagues,
> I have a 'factor' predictor called 'type' (with 4 levels). In the
> random part, I have used `||` so the levels of 'type' can't correlate
> with each other.
> But I wonder why still correlations are reported in the output?
> Thanks, Simon
> lmer(y~type + (type || ID), data = data)
> Random effects:
> Groups Name Std.Dev. Corr
> ID type0 0.4276
> type1 0.7012 0.81
> type2 0.7115 0.72 0.97
> type3 0.7655 0.83 1.00 0.98
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