• by Tyler Loechner , Staff Writer @mp_tyler, December 10, 2014

Despite a recent study from Google noting that 56.1% of all impressions served on its display platforms (including Google and DoubleClick) are not viewable, Google still tops the chart when it comes to RTB quality, at least according to one analytics provider.

Pixalate, an analytics platform for programmatic advertisers, this week released the “Global Seller Trust Index” which ranks 400 sellers by quality of ads sold via RTB. In the inaugural edition of the report, which is expected to be released monthly, Pixalate only reveals the top 20.

Google AdExchange tops the list with an overall score of 95, followed by OpenX (92), Rubicon Project (91), Centro (88) and Q1Media (86).

Now I know what you’re thinking right about now, because I thought the same thing: “How could these companies possibly have overall quality scores near or above 90 (out of 100)?!” For example, Pixalate gave Google AdExchange a viewability score of 96, which seems to fly in the face of Google’s own study saying that fewer than half of the ads bought via its platforms are not viewable.

However, the 96 score Google received for viewability — which was was among the best on Pixalate’s index, for what its worth — does not mean that 96% of ads bought via AdExchange were viewable. Rather, it means Google was better when it came to viewability compared to most of their counterparts, even if the competition wasn’t all that good to begin with.

Pixalate measured the percentage of served impressions that were viewable for each seller, according to Khalid Razzaq, the company’s VP of product. The viewability rates were then “normalized to a score between 0-99,” Razzaq said. Criteo topped the list with a viewability score of 99 (out of 99).

Pixalate rated the viewability, fraud, engagement, domain masking, network and inventory of each seller. The network score is based on domain quality, inventory is based on performance and validation, fraud is based on validated human versus bot views, viewability is based on the MRC’s standard of 50% of the ad being in-view for at least one second, engagement is based on “true user interaction” and masking compared the actual domain data to seller inventory sold.

Pixalate is an analytics client of several of the companies on the list, including Centro, but a company representative asserted that the index comes from a “different part of the business” than the analytics arm, and that “none of the data [used] for this ranking is derived from those relationships,” adding that its all based on “seller side data.”

See the top 20 sellers below. The full report can be found here.

An earlier version of this post said that Pixalate was a client of OpenX. The most has been updated to reflect that the two companies are not partners.