The Decision Trees window contains two tabs: the Selection tab and the View/Edit tab.

Selection Tab

The Selection tab contains the following panes: Decision Tree Sets, Upper Level, and Decision Trees.

Decision Tree Sets Pane

The Decision Tree Sets pane shows the available decision tree sets. The pane provides two check boxes for each decision tree set:

• The Is IncBen? check box indicates whether the set is a General or an INCBEN decision tree set, with a check mark indicating INCBEN.
• The Default in Analysis check box indicates the decision tree set that is the default for analysis (that is, the marked decision tree set is the one that the system will use if a user does not select a decision tree set for an analysis scenario).

Decision Trees Pane

The table shown in the Decision Trees pane lists all decision trees created for all decision tree sets.

Upper Level Pane

For the decision tree set selected in the Decision Tree Sets pane, the Upper Level pane shows the upper-level decision tree (as configured in the Upper Level Decision Tree window) and what lower-level decision tree(s) are assigned to each node of the upper-level decision tree. (For General decision trees, multiple lower-level decision trees can be assigned to each node of the upper-level decision tree; for INCBEN decision trees, only one lower-level decision tree can be assigned to each node of the upper-level decision tree.)
When you right-click the lowest node in the upper-level decision tree shown in the pane, the system displays a shortcut menu. This menu contains the common commands along with the following special commands:

• Assign Selected Tree: Only execute this command from the lowest level of the upper-level decision tree. For the lower-level decision tree selected in the Decision Trees pane, this command attaches the lower-level decision tree to the selected node of the upper-level decision tree. See Assign a Lower-level Decision Tree for more information.
• Remove Tree: Only execute this command from the lowest level of the upper-level decision tree. Once a lower-level decision tree is attached to a node of the upper-level decision tree, this command becomes available to sever the connection between the lower-level decision tree and the upper-level decision tree node.

View/Edit Tab

For the lower-level decision tree selected in the Decision Trees pane of the Selection tab, the View/Edit tab shows the nodes of the lower-level decision tree. Use the View/Edit tab to create and maintain lower-level decision trees by editing their structure, decision thresholds, and treatment outcomes. For parent nodes, the decision variable is shown. For child nodes, the treatment is shown (or treatments, for INCBEN decision trees). The decision tree flows from left to right, and the nodes are numbered from the top to the bottom.

When this tab is displayed, the system only displays a portion of the decision tree. You can view other parts of the decision tree by holding down the mouse key and then dragging the decision tree as desired. You can also change the magnification by using the wheel on the mouse.

Right-click Shortcut Menu Commands

When you right-click a node in the decision tree, the following special commands are displayed:

• Edit Decision Var Limits: This command is only available for nodes that have children. After selecting this command, the system displays a new window in which you select the index and thresholds that will be used to determine which treatment alternative (tree branch) will be selected. The set of decision tree variables that can be selected are configured in the Decision Variables column in the Analysis Columns Configuration window.
• Edit Treatment: This command is only available for nodes that do not have children. After selecting this command, the system displays a new window in which you select the treatment to be applied.
• Edit First Treatment Alternative: This command is only available for INCBEN decision trees and nodes that do not have children. After selecting this command, the system displays a new window in which you select the treatment to be applied if the indicated treatment cannot be applied.
• Edit Second Treatment Alternative— This command is only available for INCBEN decision trees and for nodes that do not have children. After selecting this command, the system displays a new window in which you select the treatment to be applied if neither the indicated treatment nor the first alternative can be applied.