A scientific study showed that using the reserve price feature on eBay reduces the probability of the auction resulting in a sale, deters serious bidders, and lowers the expected transaction price of the auction. A copy of the study, in which 50 matched pairs of Pokemon cards were listed on eBay - half with secret reserves and half with equivalently high public minimum bids - is available for $5.
http://papers.nber.org/papers/W8183
