[R] CART vs. Random Forest

[Andrew Baek]

I used "rpart". I should have been more clear, sorry. 

On Wed, 25 Sep 2002, Marc R. Feldesman wrote:

> At 12:51 PM 9/25/2002, Andrew Baek wrote:
>  >According to Dr. Breiman, the RF should be more accurate
>  >method than a single tree. However, the performance of each
>  >method seems to depend on the proprotion of outcome variable
>  >in my case. My data set is a typical classification problem
>  >(predict bad guys). When I ran both of them with different
>  >proportion of outcome variables(there's a criterion to measure
>  >the degree of bad behavior), I got very strange results.
>  >
>  >1. proportion of 1 to 0 = 1:4
>  >err.rate of CART = 25.2%
>  >err.rate of RF = 25.6%
>  >
>  >2. 1:9
>  >err.rate of CART = 28.5%
>  >err.rate of RF = 21.2%
>  >
>  >3. 1:33
>  >err.rate of CART = 28.2%
>  >err.rate of RF = 12.1%
>  >
>  >4. 1:99
>  >err.rate of CART = 25.1%
>  >err.rate of RF = 7.3%
>  >
>  >
>  >In 3 & 4, RF looks superior to CART. But I'm afraid RF just
>  >vote for "0" to reduce the error rate. Any suggestions?
> 
> Where are you getting CART results in R?  CART is a trademark of Salford 
> Systems and is not implemented AFAIK in R (or SPlus).
> 

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