rpart results - problem after oversampling

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Short answer: Not really.

Slightly longer answer: from what I remember of partitioning methods, a 
given split is made at either a single observation or between two 
consecutive observations. In your case, I estimate rpart would have split 
on that particular point... except that there are 6 of them now. So the 
choice of which 6 to split is arbitrary. (Someone with more knowledge of 
rpart's guts feel free to correct me).
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r-help-bounces at r-project.org wrote on 12/02/2010 05:34:23 AM:
[image removed] 

[R] rpart results - problem after oversampling

Mederos, Vicente (Santander) 

to:

r-help at r-project.org

12/02/2010 05:36 AM

Sent by:

r-help-bounces at r-project.org

Hi all,

I am trying to predict a target variable that takes values 0 or 1 
using the rpart command. In my initial dataset I have few positive 
observations of the target variable; therefore I have oversampled 
the rare event by a multiple of 6 (i.e. from 762 to 4572).

However, in my results, I end up with a number of positives in one 
of the terminal nodes that is not divisible by 6. As I have the same
observation repeated 6 times, shouldn't all of them follow the same 
branch of the tree and go to the same terminal node?

Thanks for your help,

Vicente
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