Evolution of Viewability Measurement (brought to you by the death of Flash)

There are some big changes underway in the world of viewability measurement - changes that will benefit all three constituents in the digital advertising ecosystem: advertisers, publishers, and users. The browsers are starting to make changes that will allow for significant improvements in measurement and help remove the need for Flash, but even more so effectively commoditize all viewability measurement and end discrepancies across vendors.

First, some background.

For several years, measurement vendors have employed a technique called “browser optimization” to determine viewability when their script is served within a cross-domain iframe. When inside a cross-domain iframe (on most browsers) the script does not have access to the geometric information that would normally be used to make a measurement, so the script will piggyback on browsers’ native optimization for Flash content. Browsers slow the frame rate of Flash content when it is outside the viewport, so a script can create 1x1, transparent Flash “pixels”, move them around the placement, and monitor how the browser treats them.

Not all viewability measurement companies do this (some use a statistical method called “projection”), but we do and it works very well - we get valid, verifiable viewability data. Especially in programmatic, for the roughly 30% of desktop inventory is cross-domain, it’s a critical piece of measurement technology.

However, for many reasons, using Flash is less than ideal -

  • Some users have disabled Flash in their browsers.
  • It is slower to initialize than non-Flash measurement.
  • The specific algorithm used - the number of pixels, where they’re placed, etc - is a source for measurement discrepancy between vendors.
  • Mobile devices generally do not support Flash at all, so any cross domain iframe placements on mobile web are not measurable (roughly 30% of all mobile web traffic).

What’s changing?

Certain browsers have released an optimization for HTML5 content that works very similar to the Flash optimization. It’s called "Throttle rendering pipeline based on viewport visibility”, and we’ve been able to essentially adopt our “browser optimization” measurement method to use it instead of using Flash. This is currently live for Safari version 9+ and Chrome version 52+. Not only does our measurement initialize faster, but we are now able to measure cross-domain iframe traffic on mobile devices.

Taking a look at the adoption of Chrome52 and its impact on our measurement rate -

And focusing in on mobile web -

We’ve seen similar results for Safari, which has a smaller overall footprint than Chrome, but we’re now measuring 93% of mobile web traffic vs. 50% before the change.

What’s next?

While this change represents a significant improvement to our measurement and a major step towards removing Flash, the real game-changer is Chrome’s new Intersection Observer API. It is effectively a purpose-built viewability API native to the browser. Both Firefox and Edge have indicated that they also intend to build Intersection Observer.

For users and publishers, not only will this remove the need for Flash, it could also remove the need for other common measurement script functions, like polling or certain event listening, which will further improve users' browsing experience.

For advertisers and publishers, this effectively commoditizes viewability measurement; it should be so straightforward that discrepancies between vendors all but disappear.

Where does that leave us? I believe innovation and focus will shift from viewability measurement and verification to creating seamlessly actionable viewability, which could be new real-time optimization signals or new viewable-only transactions and marketplaces, or both. We’re at an exciting inflection point and the future is bright for advertisers, publishers, and users.

Kevin Solinger is a Director of Product Management who leads our Features & Signals Capability.

Kevin Solinger

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