[R] randomForest partial dependence plots

[Christopher Schwalm]

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