There are five kinds of nodes in the Decision Tree Pane:
- Decision nodes appear as yellow squares
- Discrete Chance nodes appear as green circles
- Continuous Chance nodes appear as dark green circles
- Strategy nodes appear as yellow squares
- Controlled nodes appear as gray squares
You may use any combination of these in your decision tree. Often nodes are created in the Influence Diagram and then added to the Decision Tree. However, if you prefer to create nodes directly in the Decision Tree you can. In this case, for any node created directly in the Decision Tree, DPL also creates a corresponding Influence Diagram node.
If you have an asymmetric decision tree, some nodes may appear more than once in the tree. Each appearance of a node is called an instance of that node. Instances of a node share the common node name, states, and data from the corresponding Influence Diagram node. Properties of the each instance can be set by doubling-clicking the tree node which opens the Tree Instance tab of the node definition dialog.
Creating Nodes and Adding Instances in the Decision Tree
You may add newly created nodes directly to the Decision Tree by using the Decision Tree | Node | Add split button and placing the node directly in the tree. You can also add an instance of a node to the Decision Tree from the Influence Diagram. To do so, click on the node you would like to add in the Influence Diagram; drag and drop the node into the desired location in the Decision Tree. You may place the node directly on the connection point (blue triangle) of another node to connect it to the tree or you may temporarily place it not connected and connect it later. You may also add an instance or create a new tree node by using the Decision Tree | Instance | Add drop-down. Once selected the Select Decision(s)/Chances(s) dialog will give you the choice of adding an existing instance or adding a new instance to the decision tree. (Note: You may not create Strategy Nodes in the decision tree. Strategy Nodes must be created in the Influence Diagram, then added as instances into the Decision Tree.)
Value Nodes in the Decision Tree
Value nodes to not appear independently in the Decision Tree but they can be added via Decision Tree | Node | Add directly to the Decision Tree as a get/pay on the branches of an event. If you're in a Decision Tree-focused modeling mode (i.e., the Influence Diagram isn't visible) and want to edit a value node, choose Decision Tree | Node | Manage Values to launch the Select Values dialog.
Editing the Tree Instance of a Node
To edit the tree instance of a node, double-click it or right-click it and select Edit... from the context menu.
Tree Node Context Menu
With a node selected in addition to editing its instance, you can perform a number of other edits from its context menu including:
- Perform a subtree (endpoint must be selected in addition to node)
Versions: DPL Professional, DPL Enterprise, DPL Portfolio