In a major milestone, after a year-and-a-half-long review process, the Media Ratings Council has lifted its November 2012 Viewable Impression Advisory for Display Advertising, effectively raising the start flag for publishers to begin selling digital display advertising based on viewable impressions.

The announcement “means that—as of today—for brand advertising, agencies can and will expect guarantees on viewable display impressions. This means that one of the major obstacles to being included in brand allocations has finally been removed,” wrote Sherrill Mane, SVP, Research, Analytics and Measurement, at the Interactive Advertising Bureau (IAB) in a statement.

Mane has been the point person from the IAB on the Making Measurement Make Sense initiative (3MS), a cross-organizational group founded in 2011 to address rampant impression fraud and declining trust among marketers that the ads they were buying were actually being seen — and being seen by real people. According to comScore, over a third of display ads go unseen, and that may be conservative.

The 3MS group aimed to transition the industry from a served-impression standard to viewable-impression standard in a systematic way. They established the standard for viewable display impressions is a minimum of 50 percent of an ad’s pixels are in view for a minimum of 1 second.

The MRC initiated the advisory on viewability as a currency metric in 2012 because there was no standard for what qualified as a viewable impression. The existing measurement techniques and capabilities varied widely.

So far eleven vendors such as Google, spider.io (since acquired by Google) and the IAB with its own SafeFrame, have received MRC accreditation for their viewability measurement solutions. Today, the MRC said measurement of viewability across vendors can have a narrow variance of plus or minus 5-10 percent. The MRC is also requiring that vendors adapt their methods within 60 days.

“The Viewable Impression metric represents a huge step forward in the online advertising landscape,” said George W. Ivie, Executive Director and CEO, MRC. “By adopting this standard for viewable display impressions, the entire marketplace – agencies, marketers and publishers – will benefit from the improved quality and accountability of digital advertising. This shift will ultimately benefit the entire advertising ecosystem by paving the way to better cross-platform campaign planning and analysis.”

Google debuted viewable impression bidding on the Google Display Network in November last year.

Though the industry had warned publishers to be ready for viewability to become the new standard for branding advertising by the end of last year, Mane acknowledged “that the investment in resources is substantial” for publishers to implement viewable impressions. “You need to finance purchase of data from multiple measurement vendors, assign the right teams of people to develop test parameters, conduct enough comparisons so that you have an idea of how to forecast inventory and optimize yield. Even if all the steps are executed well, you are likely seeing variances across vendors. Some of the variances may be greater than what you’d need for confidence in the decisions you need to make.”

Viewable impressions for video is still a work in progress. The MRC is advising a gating period through June 30, 2014 before trading in viewable impressions begins. In-browser video viewability is defined as: a minimum of 50 percent in view for a minimum of 2 seconds.