I am running a CART Decision Tree, with 5 independent variables and I wonder how can I interpret the results when the same variable splits the terminal node and also splits the terminal node closest parent. For instance..

The independent variable is Income and one terminal node says x <= 11.000 "Income" and its parent says x > 5.0000, so it seems that they overlap (between 5.000 and 11.000) which can be a way to interpret or on the other hand should I only consider the terminal node figure x <= 11.000?

enter image description here The question is:

Node 18 should be “read” like the customers with income between 10.001and 15.000 OR just the customers with income above $15.000?

  • 1
    $\begingroup$ splits the terminal How on earth a terminal node can be split? The independent variable is Income The dependent variable? Please make the question clear or give a link to the picture of the tree. $\endgroup$
    – ttnphns
    Jul 13 '13 at 7:59
  • $\begingroup$ Hi I put a image of the tree on this link [IMG]i43.tinypic.com/atxgra.jpg[/IMG] $\endgroup$
    – Aureon
    Jul 13 '13 at 21:19

First, you are using "terminal node" incorrectly. The terminal nodes are the ones at the bottom of the tree that are not split.

I am pretty sure that what you mean is that a non-terminal node is split by "Income > 5000" and then the child node that answers "yes" is then split by "income < 11000". If this is the entire tree, then you have 3 terminal nodes: Income <= 5000, income between 5000 and 11,000 and income over 11,000.

  • $\begingroup$ Thank you Peter, I had a confusion with the term. I uploaded a sample image of the tree in this link [IMG]i43.tinypic.com/atxgra.jpg[/IMG] $\endgroup$
    – Aureon
    Jul 13 '13 at 21:22
  • $\begingroup$ OK, so, the two terminal nodes in that diagram split income into 2 groups, Over 15,000 and 10,000 - 15,000. Elsewhere, there must be a node (or more than one) for lower incomes. $\endgroup$
    – Peter Flom
    Jul 13 '13 at 21:25
  • $\begingroup$ Thank you Peter, so should node 18 be “read” like the customers with income between $10.001 and $15.000 OR just the customers with income above $15.000? I hesitate because the income is in both levels. $\endgroup$
    – Aureon
    Jul 13 '13 at 21:30
  • $\begingroup$ Huh? Node 11 is over 10, Node 18 is 10 to 15, node 19 is over 15, just like the labels on the nodes say. $\endgroup$
    – Peter Flom
    Jul 13 '13 at 21:35

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