William Vickrey's predicted equivalences between first-price sealed-bid and
Dutch auctions, and between second-price sealed-bid and English auctions,
are tested using field experiments that auctioned off collectible trading c
ards over the Internet. The results indicate that the Dutch auction produce
s 30-percent higher revenues than the first-price auction format, a violati
on of the theoretical prediction and a reversal of previous laboratory resu
lts, and that the English and second-price formats produce roughly equivale
nt revenues. (JEL C93, D44).