Interactive Advertising Bureau
26 March 2019

Member blog: Quality and Viewability blog series: What does viewability mean for a mobile world?

In this blog series, IAB Europe’s Brand Advertising Committee and its members explore key perspectives and the latest developments in the drive for a viewable, quality digital advertising environment.

Alex North, Head of Marketing Science R&D, EMEA, Facebook

Viewability is a measure of the opportunity for advertising value. As advertisers strive to understand mobile's unique consumption patterns and optimal marketing approaches, they're faced with new challenges that can't be solved through assumptions taken from other media.

There is universal agreement that if an ad never appears on someone's screen, then it cannot create value. But there's debate as to what counts as “viewable” once the ad has entered the screen, what standards should be employed, and how these should be applied across platforms, especially mobile. Here at Facebook, we're often asked for our perspective on the link between viewability and value as the platforms in our portfolio are used so heavily on mobile devices. Advertisers are keen to understand how consumption patterns and optimal marketing approaches are different for mobile.

It’s crucial that we explore the data available to understand how mobile platforms are consumed and how they can be used by marketers effectively: otherwise, we risk introducing bias. For example:

  • Audience bias - Duration is discussed regularly in the context of viewability, and granularity on the length of exposure is indeed important to understand. However, for platforms like Facebook and Instagram the duration of exposure is largely determined by how quickly a person scrolls through their newsfeed and their general consumption habits, and these can change dramatically from person to person. Optimising for duration could prioritise people who scroll more slowly or watch video a lot more than the average person. We've seen that there's a real difference in the age profile of those who scroll at various speeds (see the chart below). In fact, looking at Facebook internal data from December 2016 to January 2017 we found that people in their 60s scroll 2.4 times slower than people under 20. Hence if you optimise for duration you may be unknowingly paying more to reach a skewed audience.


  • Bias against short-view value - It's often assumed that duration is a reliable proxy for value, but we have found that the relationship between duration and value is not linear, and shorter exposures offer value as well. In July 2017, Oracle Data Cloud analysed 14 US campaigns on Facebook that had been previously measured for sales lift and found that long view impressions (>2 seconds) were 1.6-times more valuable for creating sales lift than short view impressions (<2 seconds) on a per impression basis. This makes sense: longer views create more value. However, the same study found that 52% of the total lift driven by video came from impressions that were under two seconds. If you focus purely on duration, and do not sufficiently account for outcomes through either a measure of campaign effectiveness or via the optimisation employed, then inventory and opportunity are left on the table.
  • Bias towards smaller ads- Smaller sized ads can more easily enter the viewable state and start counting duration sooner, and hence may be deemed more viewable than larger ads. This is pertinent for platforms such as Facebook and Instagram where ads on mobile take up the majority of the screen.

While there is universal agreement that marketers shouldn't pay for ads that don't enter the screen, it still remains an open topic on the point at which an ad is able to start creating value once it has entered the screen. Mobile environments, and particularly in-feed environments such as Facebook and Instagram, present a distinct interactive experience where users consume each piece of content before deciding to scroll to the next post. Marketers must take into account the nuances of consumption across platforms when considering where best to place campaigns. The keys to success will be a common understanding of how to quantify exposure (such as the sort of principles outlined by the European Viewability Steering Group[1]), paired with a focus on measuring the value of exposure.

[1] The EVSG principles are outlined here -

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