Is it possible that the random forest is somehow adjusting for optimism or overfitting? On Apr 1, 2014 7:27 AM, "Schillo, Sonja" <sonja.schi...@uni-due.de> wrote:
> Hi all, > > I have a question on rpart and randomforest results: > > We calculated a single regression tree using rpart and got a pseudo-r2 of > roundabout 10% (which is not too bad compared to a linear regression on > this data). Encouraged by this we grew a whole regression forest on the > same data set using randomforest. But we got pretty bad pseudo-r2 values > for the randomforest (even sometimes negative values for some option > settings). > We then thought that if we built only one single tree with the > randomforest routine we should get a result similar to that of rpart. So we > set the options for randomforest to only one single tree but the resulting > pseudo-r2 value was negative aswell. > > Does anyone have a clue as to why the randomforest results are so bad > whereas the rpart result is quite ok? > Is our assumption that a single tree grown by randomforest should give > similar results as a tree grown by rpart wrong? > What am I missing here? > > Thanks a lot for your help! > Sonja > > ______________________________________________ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide > http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. > [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
