The Tree Diagram tab contains the following elements:
This shows the nodes and branches of the fitted tree. You can examine this display to see how predictions are determined by the tree. Note how each leaf contains two blocks that provide a visual representation of the relevant statistics. The width of the black bar within the left-hand block represents the number of individuals in the leaf. The color of the right-hand block represents the mean of the treatment effect, with the color progressing from blue through gray to red as the value of the treatment effect increases.