[R] randomForest partial dependence plots
Christopher Schwalm
schw0516 at umn.edu
Sun Aug 31 02:54:26 CEST 2008
Hello ALL,
I'm unsure how to interpret partial dependence plots and had 2 questions:
Does the randomForest library scale partial dependence plots such that zero
on the y axis is mean(y)? I am also unclear as to why the range of y on
these plots is smaller than what is in the dataset.
Also I have noticed that partial dependence plots cluster around the mean
response. That is, if I'm looking at the partial dependence plot of y given
x1, x2, x3 and I standardize the x's (so they scale sensibly to be
displayed on one graph) then everything seems to meet at mean(y) and
z-score of 0 for all x's. The match is not exact but is close and shows up
in all partial dependence plots I've looked at for this particular project.
A sample graph of this is here:
img213 imagevenue com/img php?image=48746_partial_plot_122_538lo jpg
[replace spaces with dots, this bounces otherwise]
I am unsure if this means anything or if it's built in (like a SLR going
thru the mean of x an y). I should note that for this example I have
assumed that the y-axis is not scaled somehow (see first question).
Any insight appreciated. Thanks for your time.
Christopher
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