NEW YORK: Following the decisions by Facebook and YouTube to allow the Media Ratings Council (MRC) to audit their advertising metrics, pressure is growing on other digital platforms to follow suit.

A new survey of 113 members of the ANA revealed that 89% viewed independent audits as a positive development.

Around half (57%) saw them as very positive and one third (32%) as moderately positive; a further 8% were neutral and just 3% were moderately negative.

And the advertiser body upped the ante by demanding action from seven named platforms: Amazon, Foursquare, Instagram, LinkedIn, Pinterest, Snapchat and Twitter. "The ANA calls on these organizations to embrace transparency and break down their walled gardens by allowing independent audits by the MRC, " it said.

Last month both Facebook and YouTube started the ball rolling when they agreed to undergo audits by the MRC. Pinterest and Twitter are understood to have discussed a similar process.

Not so Snapchat, although it is open to third-party ad measurement. The platform fared badly in a recent ranking of social platforms in terms of ROI. It scored just 3.43 on a scale of 1 to 8, in part because of the difficulty marketers face in measuring key performance indicators and in targeting.

The growing calls for transparency that are coming from both agencies and advertisers cannot be resisted forever. The fact that the world's largest advertiser, Procter & Gamble, has declared that it regards MRC validation as its viewability gold standard, for example, has concentrated minds.

"We're accepting a shared level of error in order to conduct business on a level playing field across platforms and publishers," P&G's chief brand officer said recently. "But we expect all of our agencies, media suppliers, and platforms to adopt the standard during 2017 … We will no longer tolerate the ridiculous complexity of different viewability standards."

An particular frustration for marketers, according to Bill Duggan, exec VP, ANA, is that "they are unable to optimize if walled gardens don't open up and share data".

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