NEW YORK: A high percentage of advertisements served to mobile devices are failing to display properly but advertisers are still paying for them because the industry lacks agreed reporting standards.

A recent comScore report found that 30% of display ads are never seen by the target audiences. "It is more important than ever for advertisers to evaluate campaign viewability to improve optimization and maximize the return on their media spend," it said.

At issue is the counting process, with ad servers typically using "server-side counting" where an ad impression is counted as soon as it is requested, while advertisers would usually prefer to see "client-side counting," where an ad impression is only counted when it is successfully delivered to a device.

Apple's iAd mobile network is one that only charges for those ads that render fully on users' screens and it has become one of the first to gain accreditation from the Media Rating Council (MRC) as adhering to new standards laid down by the Interactive Advertising Bureau and the Mobile Marketing Association.

"We were favourably impressed with the range of metrics that iAd provides and their quality," David Gunzerath, senior VP and associate director of the MRC, told Advertising Age.

"It gives the buy and the sell side confidence that the measurements are accurate and can be relied upon as currency."

Others in the industry have their own take. Jim Payne, CEO of Mopub, a third-party ad server, said his company did not work with publishers whose discrepancy rate – the gap between the ads paid for and the ads that never render on a device – was above 5%.

And the Weather Co, a mobile site, said it compensated advertisers for discrepancies by offering more ad inventory than they paid for on the understanding that some would fail to render.

Another development that is likely to help digital marketers is the uptake of responsive ad units, which allow a single piece of creative to adapt itself to the device it's being viewed on.

Not only will these reduce the creative development time for multiscreen campaigns, they are also likely to enable publishers to more easily sell cross-platform packages rather than device-specific media.

Data sourced from Advertising Age, comScore, Digiday; additional content by Warc staff