They look at metrics such as whether an user immediately returns to the search results after going to a page, how long they stay at a page (relatively to other results, etc). That's the primary metric, according to a search engineer who told me during an interview.
Re:Yahoo tops Google in US traffic
by thisisnotatest on Friday August 23, 2013 @06:38PM
(#6266622)
Yes, we deal with those sorts of trade-offs every day.
I can't discuss our internal metrics, sorry.
Are you permitted to share the types of metrics that Google uses to determine whether an algorithm change is producing better results? Is bounce rate the primary metric that is used?