Prune decision trees.
Free CAS MAS-II (Modern Actuarial Statistics II) lesson in Statistical Learning. 13 min read, ~1,940 words.
Why prune: a fully grown tree has low bias and explosive variance. Pruning collapses high-variance leaves to lower test error. Cost-complexity pruning minimizes, where is the number of terminal nodes and is the complexity penalty. Weakest-link pruning produces a nested sequence of optimal subtrees, one per breakpoint. Tune by K-fold...
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What this lesson covers
- Content
- Example 1
- Example 2
- Common Mistakes
- Key Takeaways
- Exam Shortcuts
Learning objectives
- C2
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