Determine which of the following statements concerning decision tree pruning is/are true.

• The recursive binary splitting method can lead to overfitting the data.
• A tree with more splits tends to have lower variance.
• When using the cost complexity pruning method, α = 0 results in a very large tree

• None
• I and II only
• I and III only
• II and III only
• The correct answer is not given by (A), (B), (C), or (D).

Copyright 2023. The Society of Actuaries, Schaumburg, Illinois. Reproduced with permission.

Key: C

I is true because the method optimizes with respect to the training set, but may perform poorly on the test set.

II is false because additional splits tends to increase variance due to adding to the complexity of the model.

III is true because in this case only the training error is measured.

Copyright 2023. The Society of Actuaries, Schaumburg, Illinois. Reproduced with permission.