tedster - 5:03 am on Jun 25, 2007 (gmt 0)

I would think a page not being clicked on would just drop in ranking

I agree with you - but this patent is not just talking about CTR. As I read it, it's also talking about recording whether any query even taps that URL for DISPLAY, with no regard for whether there's a click.

My thinking is that if end-users rarely formulate a search that chooses a certain URL, then even if other quality factors are in place, Google may not want to include such a URL in their main index for performance reasons.

Matt Cutts recently explained that Supplemental URLs are indexed differently, with only certain keywords being flagged rather than a full text indexing. So I'm thinking that Google might move such a URL to the Supplemental Index and just flag those few search terms that have brought it up once in a while. That would save on resources -- storage, indexing and frequent crawling -- and still allow the URL to show in the few SERPs where it's needed.

Something like this could explain some of the stranger migrations I've seen, back and forth from Supplemental to Main to Supplemental.

[edited by: tedster at 6:38 am (utc) on June 25, 2007]