[R] how to measure accuracy of regression tree?

[Frank E Harrell Jr]

vibha patel wrote:
> Hello,
> 
> for constructing regression tree, I am using rpart function.
> 
> now after dividing dataset in to training and testing,
> I'm using predict for forecasting.

Such data splitting yields unreliable validations unless N > 20,000.
Frank

> 
> how to measure accuracy of the predicted data?
> 
> Thanks and Regards,
> Vibha.
> 
> 	[[alternative HTML version deleted]]
> 
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-- 
Frank E Harrell Jr   Professor and Chairman        School of Medicine
                      Department of Biostatistics   Vanderbilt University