I recently moderated a panel discussion at the 7th Annual Cynopsis Measurement & Data Conference. It included senior executives from Nexstar Digital (below), Innovid’s TVSquared and Vizio, and we discussed who they are seeing winning the ad dollars in OTT/CTV. 
The organizers recommended I show up earlier to watch previous panels to see if any themes emerged that I could leverage with my panel. So, I was able catch a debate between senior executives from Nielsen, GroupM and Roku on what constitutes (or, how we should define) an impression now that it has multiple definitions across linear, OTT and Connected TV (CTV).
Some punchy takes from GroupM’s Adam Gerber - the Executive Director, US Investment Strategy - pushed that discussion into the uncomfortable territory: “Because nothing is defined the same way, none of the ballparks are interoperable”, and that makes data like Automatic Content Recognition (ACR) “fairly worthless”. 
His point about “ballparks” is that walled gardens like streaming services and CTV devices are too walled off for their data on viewers to be more broadly applicable. At an extreme, he is reflecting a point that technology analyst Benedict Evans recently argued in an opinion for The Financial Times: “data is not one thing, but innumerable different collections of information, each of them specific to a particular application, that can’t be used for anything else.”
As Netflix, Disney+ and HBO Max pivot to advertising, I think there is an emerging question of how walled gardens - including their own - may have obstacles to success for these pivots.
The topic discussed on the panel “Impressions - The Great Equalizer?” is a complicated one. The simplest takeaway, there is no lowest common denominator standard for impressions. Meaning, an impression measured on a linear set top box [STB] is not ...