Changepoint model for Bayesian online fraud detection in call data

Tüysüz, Hilal (2018) Changepoint model for Bayesian online fraud detection in call data. [Thesis]

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Illegal use in the phone network is a massive problem for both telecommunication companies and their users. By gaining criminal access to customers' telephone, fraudsters make an illicit pro t and cause heavy tra c in the call network. After rising trend in mobile phone fraud, telecommunication companies' security departments mainly focused on increasing the e ciency of fraud detection algorithms and decreasing the number of false alarms. In this thesis, we represent an online event-based fraud detection algorithm based on Hidden Markov Models (HMM). Detection problem is formulated as a changepoint model on caller's behavior. To capture call behavior more speci cally, we split it into three parts; call frequency, call duration and call features. We prefer to adapt changepoint model for call data because of its memoryless property; the data before the changepoint does not depend on the data after the change point. To investigate the performance of our algorithm, we conducted an extensive computational study on our generated data. Our results indicate that the algorithm is practical and resampling methods can control the di culty of linearly increasing computational cost.
Item Type: Thesis
Uncontrolled Keywords: Forward-backward recursions. -- Hidden Markov Model. -- Online event-based fraud detection. -- İleri-geri yayılım algoritması. --Saklı Markov. -- Gerçek zamanlı. -- Olay esaslı dolandırıcılık tespiti.
Subjects: T Technology > T Technology (General) > T055.4-60.8 Industrial engineering. Management engineering
Divisions: Faculty of Engineering and Natural Sciences > Academic programs > Industrial Engineering
Faculty of Engineering and Natural Sciences
Depositing User: IC-Cataloging
Date Deposited: 01 Oct 2018 15:37
Last Modified: 26 Apr 2022 10:25

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