Danny Sullivan at Google again explained what the role of the search quality raters are. Again, for those who do not know, Google search quality raters are not Google employees, they are third-party contractors. They grade search results and the sites ranked. Those grades and scores do not get fed back into the algorithm, but are shared with Google's ranking engineers.
I think of it as how well you do on a test. You study all year long, get all this information into your brain and then take an exam. The exam shows the teacher how well you understand the concepts. So if a teacher has 100 students and the average grade was 90, then the teacher knows he/she is doing a good job.
With the grades given by the search quality raters, it tells the engineers how well the signals the engineers coded are doing in terms of producing good search results.
Danny explained it on Twitter as "We use raters to understand if our mix of signals seems to be producing good results. If so, then particular updates and changes get released. Then we keep working to improve with testing, new changes. It's constant improvement." It is a constant rinse and repeat, to keep tweaking out better and better search results.
He did respond to Jenny saying "That's very simplified but in the ballpark." when she said:
Is that accurate @dannysullivan? And E-A-T is the human ideal the signals are measured against, right?
— Jenny Halasz (@jennyhalasz) February 21, 2020
Forum discussion at Twitter.