[R] "prob" in predict(randomForest)
Häring, Tim (LWF)
Tim.Haering at lwf.bayern.de
Tue May 5 09:53:42 CEST 2009
Hi at all,
maybe this question is quite simple for a statistician, but for me it is not. After reading a lot of mail in the R-help archive I`m still not quite sure I get it.
When applying a randomForest to a new dataset with predict(randomForest) I have the option to get the output as probability (classification problem):
predict(myrf,...,type="prob")
I would like to know how I have to understand this output. Are this values the probability of an observation belonging to a predicted class? Say, I have a data-point as newdata, my rf-model predicts Class A and the probability is 0,12301. Does this mean that this data-point belongs to class A only with a probability of 12%?
Thanks for every hint.
TIM
Just as a matter of form: I´m using R version 2.8.1, randomForest package 4.5-28, OS: WinXP
-----------------------------------------------------------------------------------
Tim Häring
Bavarian State Institute of Forest Research
Department of Forest Ecology
Am Hochanger 11
D-85354 Freising
E-Mail: tim.haering at lwf.bayern.de
http://www.lwf.bayern.de
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