Pruning removes decision-tree splits after construction, especially partitions containing too few training examples, to reduce overfitting. It produces a simpler tree that may fit training data less perfectly but can classify new examples more reliably. section 5.1
Use pruning when a fully grown tree has become too specific:
- Work backward through the tree and remove splits enclosing very few training examples. section 5.1
- Compare pruning with limiting growth in advance, such as imposing a maximum number of splits. section 5.1
Figure 5.3 The problem handled by a simpler decision tree, obtained by pruning or by limiting its growth
Shows how pruning produces a simpler decision tree with fewer data partitions. section 5.1






