The Value of Reputation on eBay: A Controlled Experiment

Many empirical studies assess the effectiveness of reputation mechanisms, such as eBay's Feedback Forum. These investigations involve products ranging from pennies to collector guitars; they vary widely in their conclusions on how well reputation systems perform. Part of the explanation for the disparity among prior studies is that they merely collect samples from the eBay population. Such observational studies significantly increase the number of other variables that are left uncontrolled. This makes it difficult to isolate the effects of reputation on auction outcome. [

] In our main experiment, we worked with an established eBay auctioneer to sell matched pairs of items -- batches of vintage postcards -- under his extremely high reputation identity, and under newcomer identities with little reputation. Our second experiment followed the same format, but compared sales under newcomer identities with and without negative feedback. Having controlled the content of the auctions, and the presentation of item information, we were able to minimize the effects of variables other than reputation. As expected, the established identity fared better. The price difference was 7.6% of the selling price. Back-of-the-envelope calculations indicate that this amount is reasonable, given the level of risk that buyers incur. Surprisingly, one or two negative feedbacks for our new IDs had no price effects, even though these sellers had few positives.