Crossing the Channel Part 3: Ad Viewability as the New Currency


As you may recall, in our first installment of Crossing the Channel, we examined the display ecosystem from a bird’s-eye view. This time, we’ll take a deeper look into the world of ad viewability – an area of particular concern for our industry as of late.

First, let’s address a question that, up until recently, was on the tip of many busy stakeholders’ minds: Why should they even care?

For one, the IAB, ANA, 4A’s and a host of other organizations are now confronting the issue head-on. But this isn’t even the main reason most smart players are stepping up on ad viewability. The reality is that it just makes sense on both the supply and demand sides of the equation. Solving viewability gives digital advertising a huge leg up over other mediums and helps to solidify its status into the future as the industry continues to evolve to become transparent and accountable over time.

Today we’ll concentrate on how to use viewability metrics to assess your media buy’s effectiveness and efficiency. Our goal is to determine performance on any individual ad placement and creative and compare publishers across our entire media plan. To do this, we need to marry these two sets of metrics:

In order to compute performance KPIs such as Viewable CPM and Viewable CPA, we’ll need to define how we apply the viewable rate coming from the viewability vendor to the metrics measured by our ad server.

The caveat here is the metric highlighted in orange: Impressions as measured by the ad server and impressions as measured by the verification vendor. These two sets of impressions are different – sometimes as much as 80% different, in fact. There are many well-documented reasons for this. From cross-domain iframes to specific challenges with large ad formats such as homepage takeover, many variables affect why a viewability vendor might not be able to measure all the impressions served by your ad server.

(At this stage, if you feel you might need a catch-up session on viewability, there is an excellent Wikipedia Page and an IAB section that covers it very well.

So, how can you compute KPIs that need both sets of metrics (i.e. any cost-based performance metric)?

Step 1: Join data sets

This step depends on the quality of your viewablity vendor’s implementation. The golden rule here is to always use the campaign, site, placement and creative IDs from your ad server. This will enable you to join both data sets at every level where you need to assess performance.
Step 2: Calculate viewability rate
To do this, you will need to choose what to do with the ad server impressions that could not be tracked by your viewability vendor. Depending on the site placement and creative, this rate of “non-measured impressions” can be as low as 2% or as high as 60%. Mostly, this will depend on your vendors’ capabilities with cross-domain iframe measurement and other factors related to the technology of your ad.

The simple solution is to apply your viewability rate to all of your ad server impressions:

You can, of course, try to weight the viewability rate of the non-measured impression portion of your ad server impressions, but we advise against these guesses.The reasons that these impressions were not measured may have no correlation with viewability, and guessing may introduce bias into your decision-making process. Instead, as the technology evolves, you should see the rate of non-measured impressions go down on your schedule. You may also want to investigate individual site placements that show an unusually high rate.

Step 3: Optimize toward KPIs on viewable media
As you have joined your data by campaign, site, placement and creative and have calculated a rate based on your ad server impressions, you can now optimize publishers and creative according to viewable KPIs. In our example, Publisher 1 is clearly offering us more effective reach than the average of the media schedule:

With the right approach, you can standardize of your viewability calculations pretty easily. Doing so not only brings accountability for ad servers and verification vendors into focus — it also provides much deeper insights into where your spend is really going. On top of this, staying on point with viewability means being at the forefront of an industry trend that’s at the heart of every stakeholder’s mission.


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