Hand-made PageRank?

A few months ago I was pulling apart the Google Toolbar to see what kind of data was being thrown around in the background. This was nothing new, once you had the hash you could query anything.

It was interesting in two regards; the first being the PR response the toolbarqueries server returned, and the second being a much more comprehensive page of data being available (more on that later).

I couldn’t find the hash again, or get the toolbarqueries site to work in my browser, so for the moment I’m using Ethereal to pull out the server responses. Let’s see what happens on various sites:

digg.com “Rank_1:1:7″

theregister.co.uk “Rank_1:1:8″

slashdot.org “Rank_1:1:9″

cnn.com “Rank_1:1:9″

adobe.com “Rank_1:2:10″

Hello .. something’s different with that last one. Not only is it a PR 10 site, the the second parameter has changed from “1″ to “2″. Does this happen on any other sites?

nasa.gov “Rank_1:2:10″

apple.com “Rank_1:2:10″

statcounter.com “Rank_1:2:10″

Yes it does. In fact I couldn’t find a page with PR 10 without that number changing. What does it mean? I have a theory…

When it comes to ranking the web, you have to start somewhere. Back when Google first started crawling the web, no doubt Larry and Sergey popped in a few URLs and watched it explore links outward. It makes sense to continue this when calculating PRs through the index. To get the most accurate results by the 40th or 50th iteration, one could start with known trustworthy or “authoritative” pages.

I believe the second value in “Rank_1:2:10″ is exactly that – a flag saying this isn’t just any old web page, its an authoritative page. And to support this theory further, The PageRank Citation Ranking: Bringing Order to the Web paper published in 1998 has a section titled Personalized PageRank. It outlines an “important component of the PageRank calculation” and “a powerful parameter to adjust the page ranks”. This could be used to tone down PR for a site with an unusually large number of incoming links, or to adjust the PR for known authority sites in the database.

Does anyone have any information that could prove/disprove this?