Journal of Intelligent Information Systems

, Volume 36, Issue 2, pp 217–247 | Cite as

Outlier detection by example

  • Cui ZhuEmail author
  • Hiroyuki Kitagawa
  • Spiros Papadimitriou
  • Christos Faloutsos


Outlier detection is a useful technique in such areas as fraud detection, financial analysis and health monitoring. Many recent approaches detect outliers according to reasonable, pre-defined concepts of an outlier (e.g., distance-based, density-based, etc.). However, the definition of an outlier differs between users or even datasets. This paper presents a solution to this problem by including input from the users. Our OBE (Outlier By Example) system is the first that allows users to provide examples of outliers in low-dimensional datasets. By incorporating a small number of such examples, OBE can successfully develop an algorithm by which to identify further outliers based on their outlierness. Several algorithmic challenges and engineering decisions must be addressed in building such a system. We describe the key design decisions and algorithms in this paper. In order to interact with users having different degrees of domain knowledge, we develop two detection schemes: OBE-Fraction and OBE-RF. Our experiments on both real and synthetic datasets demonstrate that OBE can discover values that a user would consider outliers.


Outlier detection Outlier example Data mining Machine learning 



This research was supported in part by the Japan-U.S. Cooperative Science Program of JSPS, U.S.-Japan Joint Seminar (NSFgrant0318547), the Grant-in-Aid for Scientific Research from JSPS (#15300027), and the Beijing outstanding talents training and subsidization.


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Copyright information

© Springer Science+Business Media, LLC 2010

Authors and Affiliations

  • Cui Zhu
    • 1
    Email author
  • Hiroyuki Kitagawa
    • 2
  • Spiros Papadimitriou
    • 3
  • Christos Faloutsos
    • 4
  1. 1.College of Computer ScienceBeijing University of TechnologyBeijingPeople’s Republic of China
  2. 2.Graduate School of Systems and Information Engineering, Center for Computational SciencesUniversity of TsukubaIbarakiJapan
  3. 3.IBM T.J. WatsonHawthorneUSA
  4. 4.Carnegie Mellon UniversityPittsburghUSA

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