tedster - 3:43 pm on Feb 13, 2011 (gmt 0)
Matt Cutts publicly responded to this study on Buzz [google.com] rather than making a full blog post:
I think the phrase "successful search" is considerably less accurate than "left the site after searching," because someone can leave a site for lots of different reasons."
Hitwise later confirmed to me that they don't know whether the user actually clicked on a search result or just went to a completely unrelated site. Given all that, I'm surprised to see Hitwise is still pushing this metric and still calling it "search success rate."