NEW YORK: The American Association of Advertising Agencies will not endorse new IAB guidelines on the viewability of online ads according to reports.

A week ago the Interactive Advertising Bureau (IAB) published a position paper in which it called on the industry to move to a "70% viewability threshold" in 2015, when 70% of ads would meet agreed viewability standards

These require that at least 50% of each display ad is visible on screen for a minimum of one second and at least half of a video ad must be on screen for at least two seconds.

"It's time to set the record straight about what is technically and commercially feasible, in order to get ourselves on an effective road to 100% viewability and greater accountability for digital media," Randall Rothenberg, IAB president and CEO, said then, adding that 100% viewability was "currently unreasonable" because of the variety of ad units, browsers, ad placements, vendors and measurement methodologies made it impossible to achieve common numbers.

But the Wall Street Journal said that the 4A's had sent a letter to some of its members at the end of the week in which it stated it would "not endorse" this approach.

And Todd Gordon, evp at media agency Magna Global, was emphatic: "Running a campaign and paying for 30% of the ads not being viewable isn't acceptable to us or our clients," he said.

Last month FMCG group Unilever set its own viewability standards, requiring that 100% of an ad must be viewable in a browser; and for video, a person must click to start it rather than having it play automatically, and then they must play at least half the ad with the sound on.

Measurement issues appeared in a different guise in a new report from the video ad targeting platform, Clearstream. It suggested that 55% of video ads bought using real-time bidding are "misaligned", in that what an advertiser believes it has purchased (a video ad, say, 600x400 in size, supporting flash, positioned above the fold on a US site) is not what he actually receives (with at least one of the stated data points being wrong).

A source told MediaPost part of the problem is that there is no standard definition for video sizes and what exactly constitutes "small", "medium" and "large".

Data sourced from Wall Street Journal, MediaPost; additional content by Warc staff