Dymero - 6:33 pm on Jul 25, 2013 (gmt 0)
I'm happy to see this post, as it's another example of this phenomenon of almost instantaneous improvement in organic following a rise in sales overall, as I posted a couple weeks ago in another thread.
In our case, prices didn't change, and there was little change to our site, but people started buying in higher numbers throughout the site (not just organic) following the Independence Day weekend. The couple month period previous to that is typically slower for us.
So after sales started going up across the site, so did rankings. The opposite happened at the start of Q2, where sales across the site went down and so did rankings.
I don't think it has anything to do with sales specifically, but how it tracks visits. Google does indeed seem to be using some kind of user metrics to determine user satisfaction with a site, such as not returning to search results and more people suddenly visiting a site, and they seem to respond quickly to such rises or drops of qualified visits.