R help - Apr 2014 - Testing simple slopes for cross-level interactions

Hello,

I would like to probe a significant 2-way, cross-level interaction effect
from a linear mixed effects model that I ran using nlme.

My model is as follows:

mlmmodel <- lme(fixed = RegDiseng ~ Happy + TraitHAPPYmean +
Happy*TraitHAPPYmean,
            random = ~ Happy | ID, data = data, na.action=na.omit)

DV=RegDiseng
Level 1 variable = Happy
Level 2 variable = TraitHAPPYMean

I'd like to plot and test the significance of simple slopes a la Preacher
(i.e. http://www.quantpsy.org/interact/hlm2.htm) . I was wondering if
anyone knows a simple way to do this directly in R, so that I do not have
to extract the estimates from my R output, enter them into the website, and
then re-enter that code into R.

Many thanks!

Nastassia

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