University of Maryland researcher Chrisanthos Dellarocas recently told me how eBay reputations may be falsely inflated because people are unwilling to say mean things. He and his colleague Chuck A. Wood wrote a paper on what they call the “sound of silence” in online feedback. That silence is made by all the people who don’t add their opinions to the reputation tails. That absence of feedback, Dellarocas argues, allows certain people to garner better reputations than they should. Dellarocas says he detected a strong reporting bias in reputations on eBay and speculates that people who leave feedback are statistically more likely to be positive in their comments. Those who remain silent are likely to have squelched an urge to make a negative comment — either because they fear retribution in the form of negative scores added to their own reputation rating or because it’s simply less socially acceptable to make negative comments.