[R] Random Forest imbalanced data and partial plots

Valerie Steen
Tue, 23 Oct 2012 17:07:22 -0000

Hello,

Regarding imbalanced data: When using sampsize correction to balanced
inbalanced data in Random Forests, what are the implications of the
algorithm no longer using a bootstrapped sample? For instance, if I set
sampsize to 25, 25 for a binary response, in a dataset of N=800, how does
randomforest create a tree? Are there any reasons to not set sample size
equal?

Regarding partial dependence plots: I have gotten conflicting information
on how these are created. I believed that these were created for each
predictor with all other predictors held at their mean value. In Cutler et
al. 2007 (ecology), however, they say that all combinations of the
predictor values are used.

Thank you in advance,

Valerie

--
Valerie Steen
PhD Student, Ecology, Colorado State University
U.S. Geological Survey, Fort Collins Science Center
320-309-7237

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