TheMadScientist - 2:06 pm on Feb 28, 2011 (gmt 0)

...the fact they return to the same SERP and then click on another link, is much more telling.

But why did they return and click on another one?

Did the first one not answer the question?
Is it a new topic and they wanted confirmation of the first answer?

Why did they click on 3 different results?
Were they comparing services taking notes as they go?
Did they get conflicting answers from the first 2?

Why was the visit time longer on one than the other?
Did a site disable the back button with JS?
Or were they trying to find the answer they thought should be on the page and wasn't?

Those are only a few I can think of that don't tell you anything about correct result v incorrect result based on visit behavior ... There's too much you can't tell from click data and visit time, imo.