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 H?ring 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
"prob" in predict(randomForest)
2 messages · Häring, Tim (LWF), Liaw, Andy
In short, yes. Andy From: Haring, Tim (LWF)
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 H?ring 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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