A branch is a path segment in a decision tree. It leaves a node after a yes-or-no answer and leads to another decision node or a leaf. section 9.0
Use branches to read a decision tree from top to bottom:
- Start at the root node, which contains the first question. section 9.0
- Take the branch matching the answer to that question. section 9.0
- Continue through later branches until reaching a leaf and its decision. section 9.0
Should you wear a jacket?
Ask whether it is raining. Follow the matching branch: a rainy day immediately reaches the jacket decision; otherwise, follow a second branch based on temperature. A decision stump has only one question and two branches. section 9.0
Figure 9.2 A regular decision tree with a root node, decision nodes, branches, and leaves. Note that each decision node contains a yes-or-no question. From each possible answer, one branch emanates, which can lead to another decision node or a leaf. This tree has a depth of 2, because the longest path from a leaf to the root goes through two branches.
Visualize how each answer produces one branch and how branches connect decision nodes to leaves. section 9.0
