The concept was developed by Zoltán Gyöngyi and Hector Garcia-Molina of Stanford University in association with Pavel Berkhin and Jan Pedersen of Yahoo!.
The higher the mass measurements, the more likely the documents are to be equivalent to spam.
If their relative mass value exceeds the threshold, the documents are considered to be spam.
A second threshold for the PageRank values of the selected documents is applied.
The purpose of the methodology is to identify spam documents with artificially inflated PageRank values.