econman - 2:29 pm on Feb 26, 2011 (gmt 0)
It's essentially a massive multi-variate testing machine
I think this is the main reason we routinely see so much "everflux" in the SERPs.
On the other hand, given the way Google announced this change with such fanfare, it is likely that the changes that have just been rolled out have been verified and improved through a few months of low-profile multi-variate testing going on in the background (rather than the start of such testing).
To the extent this change has resulted in "false positives" Google will presumably struggle to find and fix those problems. Whether they succeed anytime soon is another question entirely.
As mentioned in other threads, I think the true significance of this change is conceptually related to the change in their terminology. Instead of referring to "relevance" as Google spokespersons have done for years, they are suddenly talking about "quality".
I'm not saying they have succeeded at detecting low quality. My point is simply that they are now focusing on quality in a way, or to an extent, that they have never done before.
And, quality is a subtly but fundamentally different issue than relevance.
Perhaps it is dawning on the folks at Google that negative feedback mechanisms between their algorithms and the behavior of webmasters is leading to a proliferation of junk pages, and that their emphasis on "relevance" and failure to pay attention to "quality" is the main reason they are struggling to index and analyze millions of nearly-worthless pages, as well as leading them to the criticism that their first page is filled with low quality pages that aren't particularly useful to the user. The reason those pages were ranked highly (though of low quality) is that they were created specifically to be relevant to the user's exact query.
Assuming any of these thoughts are reasonably close to being on-target, the key question is what quantitative data are they using in their new attempt to distinguish between low and high quality? And, is this data primarily at the site-wide level, or at the page-specific level?