But Knoll applauded the more precise metric. “Our data science reveals that longer ad exposures lead to better results for brands, and therefore, it's logical that we move away from the concept of a served impression, as it has no connection to whether an ad was in view or for how long,” he added.
According to IAB SVP of technology and ad operations Alanna Gombert, moving to this standard requires minimal technical adjustments. “In general, count-on-render is supported by ad servers is supported by ad servers across the board. It may require very minor tweaks on the reporting side.”
On the business side, the change may make contracts between buyers and sellers clearer. “Contracts use impressions,” Gombert said. “They bill on third-party numbers, but don’t usually delineate between rendered impressions and begin-to-render impressions.”
Start-to-render measurement adds at least a few milliseconds to when an ad counts. That latency – which would be shorter in environments like Google AMP and longer on unoptimized desktop or mobile pages – could potentially reduce the number of ads publishers have to sell. But given the fact that latency varies for numerous reasons, Gombert couldn’t predict the impact of the switch.
“It really depends on the medium where the ad is served,” she said. “There are certain sites that will load faster or slower. And fortunately or unfortunately, there is no standard load time now.”