aristotle - 2:11 pm on Jul 21, 2011 (gmt 0)
The purpose of the Panda process is to have an accurate predictive model of "shallow" content as opposed to "high quality" content. To do that, Google first asked their quality raters to create two seed sets of web pages - those that are clearly top quality and those that are obviously not.
Since one of Panda's main targets is so-called "content farms", I wonder if these quality raters may have also been asked to create a "seed set" of these content farms.
Most spam and very low quality sites should be fairly easy for Panda to identify. But many big content farms have "medium quality" content which could be harder to evaluate. So a seed set of these sites would reveal their special characteristics, and this would help make the decision easier.
I also don't think that Panda enforces a strict cutoff point somewhere between low and high quality that determines whether a site is demoted or not. Instead, I think Panda gives some kind of "quality score" to each site that determines the extent of its demotion. Thus, the lower the score, the greater the demotion.