Our ad value calculation is based on external valid data.
Print ad value is calculated from the price of full-page ad in color. Based on how much the article takes up on the pages, the value of the mention is calculated.
Ad value for web is based on the price of a top banner on the front page for 24 hours. It's not possible on all websites, so some of the ad values are estimated or similar ads are based. The estimate compares with the difference between unique number of users and ad value for other pages.