The tree Navigator is the first report CART presents when the analysis is done. It displays a high-level picture of what has been accomplished but underneath it contains complete details on every aspect of the analysis. The tree diagram shows you how complex the best model is, how accurately it predicts, and where the interesting segments are located. Let's take a closer look at some of the specifics.
In the lower right hand corner we see that our tree has 13 terminal nodes. The two bright red nodes are where the highest concentrations of BADs are to be found; the pink nodes are a little less concentrated, the white nodes are typical of the overall population and tne blue nodes contain very few BADs. Later we will drill down into our data by double-clicking on the nodes that interest us the most.
The curve under the tree diagram reports on the overall accuracy of the tree and tells us how we might trade off accuracy for a smaller simpler tree. The most accurate tree flagged by the horizontal green bar has a error rate that is 63.7% of that experienced without a model.
By clicking on another box on the error curve you will bring up a tree of different size, in this case ranging anywhere from 2 terminal nodes to over 70. We'll discuss why you might want to look at these other trees later.