Diagram of decision tree analysis pattern of classification of poor prognosis vs . good prognosis samples. The root node (top), descendant nodes and the terminal nodes (Node 1–Node 4) are shown as squares. N represents the number of samples. The first number under the root and descendant nodes is the mass value followed by the peak intensity value. For example, the mass value under the root node is 5482 Da, and the intensity is 4.911.