Output URL Bidding
In this paper, the authors study the tradeoff between the simplicity and the specification power of output bids and they explore their utility for advertisers. They first present a model to derive output bids from existing keyword bids. Then, they use the derived bids to experimentally study output bids and contrast them to input query bids. Their main results are the following: compact output bids that mix both URLs and hosts have the same specification power as more lengthy input bids; output bidding can increase the recall of relevant queries; and output and input biding can be combined into a hybrid mechanism that combines the benefits of both.