A threshold for continuous attributes is chosen using
the standard entropy minimization technique, as is
done for decision-trees. The utility of a node is computed
by discretizing the data and computing the 5-
fold cross-validation accuracy estimate of using NaiveBayes
at the node. The utility of a split is the weighted
sum of the utility of the nodes, where the weight given
to a node is proportional to the number of instances
that go down to that node