HomeTechniques and TipsPrecisionTreeSize Limits in PrecisionTree

16.1. Size Limits in PrecisionTree

Applies to: PrecisionTree 5.x–7.x

It seems my computer really drags when I create a larger decision tree or influence diagram. I know that PrecisionTree Professional Edition is limited to 1000 nodes, but are there any limits to the number of nodes in PrecisionTree Industrial Edition?

PrecisionTree Industrial does not have a limit to the total number of nodes, but large trees must be split into subtrees of no more than 5000 nodes each. You can link them into the main tree with reference nodes. Particularly if you have some repetitive subtrees, this can simplify your logic and make your tree easier to understand.  Depending on the details of the main tree and the common subtrees, you may or may not observe a speedup in calculations.

Though there's no fixed upper limit on number of nodes, there is a practical limit that varies from one computer to the next. The computational complexity of the influence diagram is proportional to the product of the numbers of branches in all the nodes. That means that you get slower and slower performance as you have more and more nodes. A thousand, for instance, would almost certainly be too many. But there's no one number where we can say, "no more than this", because it depends on the characteristics of the computer.

Similar considerations apply with a decision tree. And, even though a decision tree lets you split a portion off into a subtree, this does not reduce the computational complexity.

Last edited: 2015-10-20

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