%0 Report %9 Technical Report %A Gyongyi, Zoltan %A Berkhin, Pavel %A Garcia-Molina, Hector %A Pedersen, Jan %D 2005 %F ilprints:697 %I Stanford InfoLab %K web search; link spam detection %T Link Spam Detection Based on Mass Estimation %U http://ilpubs.stanford.edu:8090/697/ %X Link spamming intends to mislead search engines and trigger an artificially high link-based ranking of specific target web pages. This paper introduces the concept of spam mass, a measure of the impact of link spamming on a page's ranking. We discuss how to estimate spam mass and how the estimates can help identifying pages that benefit significantly from link spamming. In our experiments on the host-level Yahoo! web graph we use spam mass estimates to successfully identify tens of thousands of instances of heavy-weight link spamming.