Online ads are massive, accounting for about 20 percent of total spending in the advertising industry, and more than 90 percent of Google’s and Facebook’s revenues. But a new report from Google admits that more than half of them – 56. 1 percent – are never seen by anyone.

Google said more than half the ads it serves are never “in view”, or seen on-screen for one second or more. That means a massive number of “impressions” advertisers pay for are never actually seen.

This actually isn’t a huge revelation. Only last year the Internet traffic analysis firm ComScore claimed that 46 percent of all ads are never “in view”. And earlier this year the advertising fraud company Spider.io said a single botnet of 120,000 malware-infected PCs was responsible for billions of ad impressions, all of which were paid for by advertisers without any humans ever seeing them.

Nevertheless, this is the first time that the web’s largest advertising company has acknowledged the problem. The news could have some big repercussions – including delaying some ad company’s IPOs, and possibly even leading to a demand for a new way to gauge ad effectiveness.

Nineteenth-century retailer John Wanamaker, considered to be a ‘pioneer’ in marketing, once said “Half the money I spend on advertising is wasted. The trouble is I don’t know which half.” Now it’s something that applies to almost every advertising firm that dabbles in the web.

It isn’t immediately clear why Google has only admitted to the problem now, though the admission comes just a few months after it rolled out a new product called “Active View”, that only measures ads that have been seen by real humans.

photo credit: adamrhoades via photopin cc