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Influence the automatic build process

To influence the automatic build process, either wait for the tree to stop growing, or click the Pause button while it is still growing.

Before growing the tree further, you can:

You can then continue to use the automatic build process, but influencing how it is applied:

Or you can take full manual control of the build process - see How do I manually control the build process?

For suggestions on how to use these options see Suggestions for influencing the build process.

Note that you cannot modify the base or analysis selections without rebuilding the tree. Also you cannot modify a tree which has been saved and then restored.

Growing a specific node

To grow from a single leaf node, Right click on the node in any of the Tree Views and select:

  • “Grow single step from this node” to create one additional split from this node.

  • “Grow continuously from this node” to restart the automatic build process, growing just this node and any subsequent child nodes, continuing until a Stopping Condition is met.

You can also grow from any of the leaf nodes at the end of a branch, by clicking on the branch itself and selecting:

  • “Grow single step from leaf nodes" to create one additional split from one of the leaf nodes at the end of this branch. The node and split to use are chosen according to the Algorithm Options.

  • “Grow continuously from this node” to restart the automatic build process, growing just the leaf nodes at the end of this branch and any subsequent child nodes, continuing until a Stopping Condition is met.

A dotted line will appear across the ends of all other nodes to indicate that they are being prevented from growing.

Stopping sections of the tree

It may be easier to specify which part of the Decision Tree you wish to grow, by actually specifying the parts you don’t want to grow.

To stop a whole branch, right click on a node and select “Stop leaf nodes from growing”. In the first diagram, all leaf nodes that are beyond the node highlighted will be stopped from growing. A line is drawn across the end of the node to indicate this (see leaf nodes in the second diagram).

To allow nodes to grow which have been stopped in this way, right click on the particular node and select “Allow this node to grow”, as shown in the second diagram.

Having set up which nodes should be stopped, then click on the Play button to allow the Decision Tree to grow. The whole Decision Tree will then grow, but only the nodes which have not been stopped as above will be grown.

Note that the “Grow now from leaf nodes” option will override any stopped nodes.

Pruning a branch of the tree

A branch of the tree can be permanently removed by right clicking on the node itself and selecting "Prune all nodes beyond here". The node you click on will remain, but all nodes beyond will be removed. They can only be restored by regrowing the branch using the same build options as before.

Pruning enables the user to experiment with alternative trees, perhaps growing using one variable and then trying again with a different one.