We run a series of controlled field experiments on eBay where buyers are
rewarded for providing feedback. Our results suggest that the feedback
rate increases when a rebate is given, though the effect is small.
Moreover, the nature of buyer feedback is influenced by rewards: buyers
are more likely to give positive feedback following a high-quality
transaction (fast shipping) and less likely to give negative feedback
following a low-quality transaction (slow shipping). In sum, you can buy
feedback but you cannot buy unbiased feedback