Mohsen Rezvani, Aleksandar Ignjattovic, Elisa Bertino
Tech report number
CERIAS TR 2017-2
Online rating systems are widely accepted as means for quality
assessment on the web and users increasingly rely on these systems when deciding to purchase an item online. This makes such rating systems frequent targets of attempted manipulation by posting unfair rating scores. Therefore, providing useful, realistic rating scores as well as detecting unfair behavior are both of very high importance. Existing solutions are mostly majority based, also employing temporal analysis and clustering techniques. However, they are still vulnerable to unfair ratings. They also ignore distances between options, the provenance of information and different dimensions of cast rating scores while computing aggregate rating scores and trustworthiness of users.
In this paper, we propose a robust iterative algorithm which leverages information in the profile of users and provenance of information and which takes into account the distance between options to provide both more robust and informative rating scores for items and trustworthiness of users. We also prove convergence of iterative ranking algorithms under very general assumptions which are satisfied by the algorithm proposed in this paper. We have implemented and tested our rating method using both simulated data as well as four real-world datasets from various applications of reputation systems. The experimental results demonstrate that our model provides realistic rating scores even in the presence of a massive amount of unfair ratings and outperforms the well-known ranking algorithms.
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