Modifications of classification strategies in rule set based bagging for imbalanced data

  • Authors:
  • Krystyna Napierala;Jerzy Stefanowski

  • Affiliations:
  • Institute of Computing Science, Poznań University of Technology, Poznań, Poland;Institute of Computing Science, Poznań University of Technology, Poznań, Poland

  • Venue:
  • HAIS'12 Proceedings of the 7th international conference on Hybrid Artificial Intelligent Systems - Volume Part II
  • Year:
  • 2012

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Abstract

Learning bagging ensembles of rule classifiers from imbalanced data is considered. We claim that simply introducing bagging instead of single classifiers may not bring the expected improvement in recognizing a minority class. The reason lies in the classification strategies of component classifiers, which are biased toward majority classes when no-matching or multiple-matching conflicts between rules occur. We argue that abstaining, i.e. allowing component classifiers to refrain from giving a prediction in ambiguous situations, may help to correctly recognize minority examples. Our evaluation on 17 imbalanced datasets and 5 classification strategies shows that bagging with abstaining is better than both standard bagging and single rule based classifiers.