The new ranking model is designed to allow.
The new ranking model is designed to allow advertisers to focus less on competitive bidding practices and more on the quality of their ads. An ad’s quality will primarily be determined by its historical performance—its click-through rate relative its position in search results—as well as its expected performance relative to other ads displayed at the same time..
Original text search at: ypnblog.com/blog/2007/01/