Forest Pruning Based on Branch Importance

Area of Science:

• Machine Learning
• Ensemble Methods
• Decision Trees

Background:

• Ensemble methods, particularly decision tree forests, are powerful machine learning models.
• Pruning is crucial for optimizing ensemble performance and reducing computational complexity.
• Existing pruning methods often overlook the ensemble's overall generalization ability.

Purpose of the Study:

• To propose a novel strategy for pruning decision tree forests.
• To enhance ensemble generalization ability and reduce ensemble size.
• To introduce a new metric, 'importance gain', for evaluating branch importance within an ensemble.

Main Methods:

• A new metric, 'importance gain', is proposed to evaluate branch importance.
• Importance gain considers both ensemble accuracy and the diversity of ensemble members.
• The method prunes branches based on their contribution to ensemble performance.

Main Results:

• The proposed pruning strategy significantly reduces ensemble size.
• Ensemble accuracy is demonstrably improved by the novel pruning method.
• The method shows effectiveness across different ensemble construction algorithms (e.g., bagging) and tree pruning strategies.

Conclusions:

• The 'importance gain' metric offers an effective way to prune decision tree ensembles.
• This approach enhances generalization and reduces model complexity.
• The method is robust and applicable to various ensemble configurations.