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Random Forest
2 messages · Unger, Rachel, Peter Langfelder
On Tue, May 24, 2011 at 3:18 PM, Unger, Rachel
<rachel.unger at cahnrs.wsu.edu> wrote:
I'm analyzing data using Random Forest Regression. ?For some of the species I am analyzing, the percent variation explained is negative. Could you please explain to me what that means? ?If you need more information, please let me know. ?Thank you.
If you're using the rsq component of the randomForest output, negative value means the mean error is larger than the variance of the response y. This could be because the predictor performs really poorly but also because of some calibration issue. You may want to consult someone face to face to diagnose the problem. As a start, I would look at a scatterplot of observed vs. predicted values to see whether there is a systematic effect HTH, Peter