Decision Tree Classification with 0 on BOTH terminal nodes of branches?

Using t=fitctree(x,y,'MinLeaf',20) and then view(t,'Mode','Graph') to look at how the tree is working, and I see that in several cases the result at a terminal branch is for BOTH end points to be '0', or BOTH to be '1'.

How can this be? I would expect each branch to end with one '0' and one '1', never two '0' or two '1'.

Thanks!

Answer 1

[Ilya]

Nothing wrong with that. A classification tree optimizes the Gini index and can split a parent node in two child nodes dominated by the same class.

[Justin]

OK so I'm thinking that the two leaf nodes can both be for say, 0 but be grouped as different levels of 'closeness' to 0 as compared to 1...Thanks00