TheMadScientist - 7:03 am on Jan 13, 2013 (gmt 0) [edited by: TheMadScientist at 7:10 am (utc) on Jan 13, 2013]
Take that into consideration how though is the question? (Taking into consideration is still way different than using directly.)
What they've openly stated (relating to Panda or Penguin), and I believe them, is they checked the sites hit by the algo against the Chrome block list and got 84% or 86% of the most blocked sites right from the start ... They didn't 'use the blocks' in the algo, they verified the algo against the 'blocks'.
As far as Chrome goes, 33% market share leaves 67% 'unknown' and that's a big % to 'not know about' and a Huge number of people when you're talking about 500,000,000 regular Internet users (based on Facebook usage only) and if you figure Chrome users visit a 'relative to the whole' number of sites and pages that's a big number of 'data missing' holes from 125,000,000+ dot com sites alone (never mind how many pages those sites have or any other tlds and their pages).
When you think page/visitor information, there's actually more available via Analytics than Chrome, just based on sheer usage per page numbers ... I don't remember them off the top of my head though, but I know, last I heard, Analytics had way more coverage than Chrome overall, and AdSense likely has the most, but still, it's not 'the whole Internet', which is what they're trying to sort, organize and rank for all their visitors, not only 'certain segments' of it represented by the data they have access to from different avenues.
I still stick with: The algos have to cover the whole thing.
Not trying to rant at you, just explain.
[edited by: TheMadScientist at 7:10 am (utc) on Jan 13, 2013]