From AdAge in an article entitled: "ComScore Study Confirms What We Already Knew: You’re Wasting Money on Ads No One Sees"
One of the key findings: 31% of the 1.7 billion ad impressions were
never in view. The number is probably not a shock to many in the space,
and is the main reason why so-called remnant inventory sells for a
fraction of the space above the fold. But with this knowledge,
advertisers can more accurately manage expectations and calculate ROI,
said ComScore CEO Magid Abraham.
Not a huge surprise- online display ads have always produced very poor results. Full story here
The Print Observer - Newspaper & Magazine Advertising Insights 