[R-sig-ME] Why || doesn't zero out the correlations in lmer
@|m@h@rme| @end|ng |rom gm@||@com
Sat Oct 9 00:07:08 CEST 2021
Thank you, this is extremely helpful to know. You mentioned it's well
documented, any possible links to share?
Also, does nlme::lme() behave in the same manner in this regard?
On Fri, Oct 8, 2021 at 4:46 PM Phillip Alday <me using phillipalday.com> wrote:
> 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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> > https://stat.ethz.ch/mailman/listinfo/r-sig-mixed-models
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