Art experts and auctions Are pre-sale estimates unbiased and fully informative?

Public sales art catalogues include low and high pre-sale price estimates by experts. This makes it possible to analyze whether pre-sale estimates are unbiased predictors of realized prices. Unbiasedness is tested using a sample of some 1,600 lots of English silver auctioned by Christie's and Sotheby's. Results show that estimates are slightly (but significantly) baised and that experts do not use ail the information that is available to them when they make their estimates.