On 03.05.2010 04:26, Claudia Penaloza wrote:
I ran this code (several times) from the Quick-R web page (
http://www.statmethods.net/advstats/cart.html) but my cross-validation
errors increase instead of decrease (same thing happens with an unrelated
data set).
Why does this happen?
Since the classes are not well separable along the dimensions using the
provided variables?
Am I doing something wrong?
Wrong is that you expect the result to be always better if the tree is
larger.
Try the iris data, for example, and find that your assumptions are not
always wrong. ;-)
Best wishes,
Uwe
# Classification Tree with rpart
library(rpart)
# grow tree
fit<- rpart(Kyphosis ~ Age + Number + Start,
method="class", data=kyphosis)
printcp(fit) # display the results
plotcp(fit) # visualize cross-validation results
Thank you,
Claudia
[[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.
______________________________________________
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.
