Planet13 - 2:13 pm on Nov 12, 2011 (gmt 0)
There's a lot in that statement if you unpack it, because it implies that it is an indirect or emergent factor in Panda -- that while Panda isn't actually measuring the percentage of ads directly, it is measuring things (presumably behavioral metrics) that might be impacted by ad positioning.
I think you hit the nail on the head.
But again, you have the problems of measuring user behavior on sites that don't have google analytics installed.
Traditionally, pundits believed that the "back to serps" speed (i.e., how quickly a visitor who clicked on a SERP result returned to the SERPs to look at other results)was the most "reliable" metric, since google could measure that rate with pretty high certainty.
So, what exactly were they measuring, and how?