The Strength of Weak Learnability
Machine Learning
Machine Learning
Machine Learning
Bayesian Averaging of Classifiers and the Overfitting Problem
ICML '00 Proceedings of the Seventeenth International Conference on Machine Learning
Pattern Classification (2nd Edition)
Pattern Classification (2nd Edition)
Constructing diverse classifier ensembles using artificial training examples
IJCAI'03 Proceedings of the 18th international joint conference on Artificial intelligence
Criteria Ensembles in Feature Selection
MCS '09 Proceedings of the 8th International Workshop on Multiple Classifier Systems
When efficient model averaging out-performs boosting and bagging
PKDD'06 Proceedings of the 10th European conference on Principle and Practice of Knowledge Discovery in Databases
Biclustering-driven ensemble of Bayesian belief network classifiers for underdetermined problems
IJCAI'11 Proceedings of the Twenty-Second international joint conference on Artificial Intelligence - Volume Volume Two
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Ensemble techniques such as bagging and DECORATE exploit the "instability" of learners, such as decision trees, to create a diverse set of models. However, creating a diverse set of models for stable learners such as naïve Bayes is difficult as they are relatively insensitive to training data changes. Furthermore, many popular ensemble techniques do not have a rigorous underlying theory and often provide no insight into how many models to build. We formally define stable learner as having a second order derivative of the posterior density function and propose an ensemble technique specifically for stable learners. Our ensemble technique, bootstrap model averaging, creates a number of bootstrap samples from the training data, builds a model from each and then sums the joint instance and class probability over all models built. We show that for stable learners our ensemble technique for infinite bootstrap samples approximates posterior model averaging (aka the optimal Bayes classifier (OBC)). For finite bootstrap samples we estimate the increase over the aBC error using Chebychev bounds. We empirically illustrate our approach's usefulness for several stable learners and verify our bound's correctness.