iBoost: Boosting using an instance-based exponential weighting scheme

  • Authors:
  • Amitava Karmaker;Kihoon Yoon;Chau Nguyen;Stephen Kwek

  • Affiliations:
  • University of Texas at San Antonio, San Antonio, TX 78249, USA. E-mail: akarmake@cs.utsa.edu;University of Texas at San Antonio, San Antonio, TX 78249, USA. E-mail: akarmake@cs.utsa.edu;University of Texas at San Antonio, San Antonio, TX 78249, USA. E-mail: akarmake@cs.utsa.edu;University of Texas at San Antonio, San Antonio, TX 78249, USA. E-mail: akarmake@cs.utsa.edu

  • Venue:
  • International Journal of Hybrid Intelligent Systems
  • Year:
  • 2007

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Abstract

AdaBoost is a well-recognized ensemble method to improveprediction accuracy over the base learning algorithm. However, itis prone to overfitting the training instances [18]. Freund,Mansour and Schapire [5] established that using exponentialweighting scheme in combining classifiers reduces the problem ofoverfitting. Also, Helmbold, Kwek and Pitt [7] showed in theprediction using a pool of experts framework an instance-basedweighting scheme improves performance. Motivated by these results,we propose here an instance-based exponential weighting scheme inwhich the weights of the base classifiers are adjusted according tothe test instance x. Here, a competency classifier c_i isconstructed for each base classifier h_i to predict whether thebase classifier's guess of x's label can be trusted and adjust theweight of h_i accordingly. We show that this instance-basedexponential weighting scheme enhances the performance ofAdaBoost.