[R-sig-ME] LMER: Visualizing three-way interaction

[Evan Palmer-Young]

Dear Klemens,
I also have been asked to remove plot3d plots that I thought were
stupendous, but I guess not everybody likes them!
How about two two-way interaction plots for the regressions of continuous
variable 1 vs 2, with separate panels for the levels of the categorical
variable?
You can get fitted model values and CI's with the lsmeans function, using
the "at" argument to specify covariate values.
If the plot is too bland, you can sprinkle the raw data on top as an extra
layer of points.
Best wishes, Evan


On Wed, Apr 12, 2017 at 5:41 AM, Klemens Knöferle <knoeferle at gmail.com>
wrote:

> Hi all,
>
> I'm trying to visualize a three-way interaction from a rather complex
> linear mixed model in R (lmer function from the lme4 package; the model has
> a complex random-effects structure). The interaction consists of two
> continuous variables and one categorical variable (two experimental
> conditions).
>
> So far, I have graphed the interaction via two 3D-surface plots using
> visreg2d from the visreg package. But my reviewers found these plots
> confusing and asked for a different illustration, such as conditional
> coefficient plots (i.e., plots of the strength of coefficient 1 as
> coefficient 2 increases).
>
> I've tried to find a package that allows me to create these kind of plots,
> but failed. The existing packages only allow coefficient plots for two-way
> interactions (for instance the interplot package;
> https://cran.r-project.org/web/packages/interplot/
> vignettes/interplot-vignette.html).
> That means I only get a conditional coefficient plot of the two-way
> interaction, collapsed across both levels of the categorical variable.
>
> Is there a package for my case? If not, I probably have to manually extract
> fitted values from my model (e.g., using broom) and somehow plot them in
> ggplot2. But I don't really know how to do this, whether or not to take
> into account random effects (and how), etc. Any ideas would be much
> appreciated...
>
> Klemens Knöferle, Ph.D.
> Associate Professor - Department of Marketing
> BI Norwegian Business School
> Visiting address: Nydalsveien 37, 0484 Oslo
>
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>
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-- 
Evan Palmer-Young
PhD candidate
Department of Biology
221 Morrill Science Center
611 North Pleasant St
Amherst MA 01003
https://sites.google.com/a/cornell.edu/evan-palmer-young/
epalmery at cns.umass.edu
ecp52 at cornell.edu

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