Buying reputation on eBay: Do recent changes help?

This paper uses simple repeated field experiments to show how eBay's reputation system can be manipulated by purchasing cheap positive feedbacks, and proposes a simple alternative fee policy likely to improve the reliability of the mechanism.

Abstract

In this paper we use simple repeated field experiments to show how eBay's reputation system can be manipulated by purchasing cheap positive feedbacks. Our experiments confirm that 'feedback purchase' is still possible even under the new rules that eBay recently adopted to eliminate 'padding'. In discussing these rules we conclude that changes have strengthened the reliability of the feedback mechanism with respect to 'retaliatory' behaviours, but have weakened it with respect to 'feedback purchase'. Finally, we discuss the possible impact of feedback manipulation on eBay and analogous e-commerce platforms, and propose a simple alternative fee policy likely to improve the reliability of the mechanism.