By Ian Hewetson

In case you missed this mini scandal, Facebook recently revealed that for the past two years (!) it had been supplying erroneous video engagement numbers to advertisers. And, naturally, it wasn’t that the company had been underestimating the numbers – their reports actually significantly overstated results.

Reaction amongst advertisers ranged from shrugs to outrage; and the issue has now passed out of the media news cycle. But apart from the obvious questions about Facebook’s reporting accuracy, this story has cast a new light on how important it is for advertisers to know what they’re buying and how it’s measured.

As an advertiser, it’s critical that you should know exactly how the numbers you’re looking at are calculated. This is true about any reporting, but especially if you’re dealing with multiple walled gardens who supply their own results.

If campaigns are running directly on any publisher or platform, there’s no guarantee that each one even uses the same definitions or methodologies. And that’s before you start thinking about actual errors on the supply side.

The only real way to get all your media suppliers on a level playing field is to use a third-party ad server, which monitors your results across multiple channels, and expresses every metric using the same methodology. Measuring all of your media independently also reveals supply side issues – for example, the Facebook reporting error would have been caught by advertisers within a few hours, rather than years, if Facebook had allowed third-party ad serving.

One of the key advantages of digital is that it’s meant to be far more measurable and accountable than legacy media, but when key platforms forbid third-party tracking, they erode the advantages of the online medium.

Even putting accountability aside, when walled gardens deny third-party ad serving, they’re denying the advertiser the chance to know more about their audiences, and disabling some of the essential methods of media optimization.

One of the obvious reasons that third-party ad servers are used so widely is that they allow for centralized reporting – which vastly increases the likelihood of media buys being optimized between different media sources; and optimization leads to greater media efficiency.

Possibly less obvious are the benefits of being able to see the locations, device types and behavioural profiles of users wherever they’re interacting with advertising. It’s also becoming more important for advertisers to have the ability to update their own DMPs and CRM systems when a user engages with their brand. When third-party ad serving is restricted from a media source, all of this goes out the window.

Frequency is one of the most influential factors in media buying efficiency, and it’s impossible to measure frequency unless you’re de-duplicating users who see your message on multiple platforms, and the only way to de-duplicate is through third-party adserving.

It’s easy to see how we’ve come to this point – with the vast majority of online media dollars spent on a very few platforms, those platforms now wield the power to make the rules – and these rules are specifically designed to keep dollars within the walls of each garden.

Ironically, it’s advertiser dollars that pay to maintain the walls that actually hurt them. As the Facebook example illustrates so well – maybe it’s time for advertisers to demand more accuracy, accountability and efficiency from their media sources.

Ian Hewetson is VP of client services at Eyereturn Marketing.