tedster - 3:08 am on Oct 10, 2012 (gmt 0)
But as Tedster has pointed out here, they were using bounce.
More exactly, there's reason to think that Google uses a fast bounce metric (bouncing quickly back to the SERP.) Anything more than that is my guesswork, and I'm sorry if I misled anyone into thinking it was a proven fact. Just the fast bounce, or click-back rate factoring in the time involved, doesn't require any Analytics leaking into the algorithm.
What we know for sure and what is our best guess are two different things.
I DO encourage SEOs to use a kind of adjusted bounce rate from their analytics, one that accounts for time-on-page as well as the bounce. Hold on to your traffic with content that clearly works for them - not just content that ranks. If you see evidence that content isn't working for your visitors, dig in and fix it.