Robert_Charlton - 6:07 pm on Sep 24, 2012 (gmt 0)
Keeping a QDF change as a possibility, I also very much agree with tedster on this point with regard to the role of human raters...
...human raters are used to assess changes in the algorithm before they go live. They do not rate individual live SERPs.
Judging by the new Rater's Guidelines, in early stages they're tagging sites and pages which are considered in early test algorithms, before these are rolled out publicly. These are cross-confirmed and cross identified in a great many ways, including ways which are independent of the evaluators.