arbor
object.
plotcp(x, minline=T, lty=3, col=1,
upper=c("size", "splits", "none"), ...)
arbor
The set of possible cost-complexity prunings of a tree from a nested
set. For the geometric means of the intervals of values of
cp for which
a pruning is optimal, a cross-validation has (usually) been done in
the initial construction by
arbor. The
cptable in the fit contains
the mean and standard deviation of the errors in the cross-validated
prediction against each of the geometric means, and these are plotted
by this function. A good choice of
cp for pruning is often the
leftmost value for which the mean lies below the horizontal line.