This ranking mechanism is a loglikelihood algorithm which compares the key words in the first box to those in the second.
This mechamism is also used in the Issue Feed where only key words with a deviance in the 95th significance percentile are shown in the list.
When an Issuecrawler xml file is provided, all the urls in the network will be retrieved and the significance of the words of each page will be calculated compared to all the worlds of all the pages in the network.