Hunting for fraudsters in random forests

  • Authors:
  • R. M. Konijn;W. Kowalczyk

  • Affiliations:
  • Department of Computer Science, Faculty of Sciences, VU University, Amsterdam, The Netherlands;Department of Computer Science, Faculty of Sciences, VU University, Amsterdam, The Netherlands

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

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Abstract

In this paper we present a hybrid method for identifying suspicious behavior in transactional data by combining techniques from outlier detection and subgroup discovery. Most existing outlier detection approaches focus on the identification of single outliers without providing a description of these outliers. Moreover, these methods find single outliers instead of groups of outlying records. However, when searching for fraud, it is important to analyze data not on the level of single records but on a higher, group level, such as sets of records of customers, shops, etc. Our method is able to analyze data on such a higher level and additionally it provides descriptions of groups of found outliers. The method involves three steps: scoring of individual records with help of a newly proposed outlier measure which is calculated with help of random forests, identification of unusual groups of records with help of subgroup discovery techniques, and finally, identify the most deviating entities such as shops, hospitals.