Investigating Shill Bidding Behaviour Involving Colluding Bidders

Abstract

Abstract-Shill bidding is where spurious bids are introduced into an auction to drive up the final price for the seller, thereby defrauding legitimate bidders. Trevathan and Read presented an algorithm to detect the presence of shill bidding in online auctions. The algorithm observes bidding patterns over a series of auctions, and gives each bidder a shill score to indicate the likelihood that they are engaging in shill behaviour. While the algorithm is able to accurately identify those with suspicious behaviour, it is designed for the instance where there is only one shill bidder. However, there are situations where there may be two or more shill bidders working in collusion with each other. Colluding shill bidders are able to engage in more sophisticated strategies that are harder to detect. This paper proposes a method for detecting colluding shill bidders, which is referred to as the collusion score. The collusion score, either detects a colluding group, or forces the colluders to act individually like a single shill, in which case they are detected by the shill score algorithm. The collusion score has been tested on simulated auction data and is able to successfully identify colluding shill bidders.

Detecting Collusive Shill Bidding

“…We refer to the strategies a group of shill bidders can engage in as collusive shill bidding [19,20]. We investigated approaches to shill bidding involving one seller who controls multiple shill bidders and what effect this has on the Shill Score.…”

“…In [19,20] we describe how to extend the Shill Score to detect collusive shill bidding behaviour using a Collusion Score. While the details this approach are outside the scope of this paper, the purpose of this discussion is to highlight how differing collusive behaviours can be used in an attempt to influence the Shill Score.…”

A Run-Time Algorithm for Detecting Shill Bidding in Online Auctions

“…However, their proposed shill bidding detection algorithm does not work in real-time. Later, Trevathan and Read [27] improved their previous work by proposing a method to detect colluding shill bidding where multiple bidders participate in shill bidding activities under a group. The authors introduce a score called Collusion Score which can detect a colluding group that involves in shill bidding activities [27].…”

“…Later, Trevathan and Read [27] improved their previous work by proposing a method to detect colluding shill bidding where multiple bidders participate in shill bidding activities under a group. The authors introduce a score called Collusion Score which can detect a colluding group that involves in shill bidding activities [27]. The Collusion Score combines all the Shill Score ratings and gives each bidder a score based on the likelihood that they are engaging in collusive shill bidding activity [27].…”

“…The authors introduce a score called Collusion Score which can detect a colluding group that involves in shill bidding activities [27]. The Collusion Score combines all the Shill Score ratings and gives each bidder a score based on the likelihood that they are engaging in collusive shill bidding activity [27]. However, their proposal works only when an auction ends.…”