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Impressions vs Exposures: Who Saw My OOH Ad?

January 19, 2023

Measuring Out-of-Home advertising effectiveness can seem complicated. It is getting more difficult to measure advertising based on mobile ad ids and to truly know who saw your outdoor ad in the physical world. Also, the terminology can be confusing to those who don’t work regularly in the space.

In this article, we explain the difference between impressions as they are typically calculated by organizations such as Geopath and Billups audience exposures. This will help you understand how both can be used to plan, execute and measure outdoor advertising campaigns.

What are Impressions and How are they Calculated? 

Impressions are estimates of how many eyes could have been on your campaign. They are commonly used in OOH media planning because they fold into Cost Per Thousand (CPMs) when buying outdoor ad units. Impressions are usually provided per unit by the media owner and are based on the unit’s past performance.

Organizations like Geopath, the United States’ OOH industry standard ratings organization, provide impression estimates for a given piece of inventory. Brands and advertisers rely on these estimates heavily in the planning process because impressions suggest what will likely happen in a given campaign. 

What are Exposures and How are they Calculated? 

Exposures are predictions that are validated by mobile device data and can indicate what actually happened in a campaign. At Billups, they are calculated using a computer vision system that assesses OOH inventory and viewability. This automatically detects OOH placements to show from what precise locations the inventory can be seen, also known as the viewshed. 

Visual representation of the viewshed. The green area represents the optimal field of view for an OOH unit and the blue and orange symbols represent the probability a person will be able to see the OOH unit from that viewpoint and for how long.

Exposures, as Billups calculates them, are unbiased in that they are based completely on geospatial and market data. The Billups Opportunity to View (OTV) patent shows the opportunity to see a unit based on robust mobile device data input. OTV refers to the number of opportunities that a particular audience has to see a specific advertisement.

Many People Opt Out of Mobile Tracking on Their Devices. How Does this Affect the Counts? 

Just like a doctor only needs to take a small amount of your blood to gain useful information about your health, mainly a small fraction or percentage of the market needs to have their device opt-in to the mobile pings. This allows us to know whether or not your audience likely saw the ad.

While not perfect, mobile data is the current and best solution for a data point that represents the potential viewers of an OOH ad. Their mobile location data informs where they were in proximity to our OOH campaign.

What's the Difference Between an Impression and a Billups Exposure?

Geopath impressions and Billups exposures are calculated differently. Geopath impression estimates rely on data across multiple vendors and sometimes self-reporting from publishers. They do not apply mobile data as frequently. On the other hand, Billups exposures are calculated using a patented computer vision system that assesses the area from which OOH inventory can be viewed. This creates predictions which are then validated by mobile device data to determine what actually happened in a campaign. Because Billups exposures are based on geospatial, market and robust mobile device data inputs, they are supplier agnostic and provide more accurate view counts.

Geopath impressions and Billups exposures are also used differently. Geopath impression counts are used in the planning of a campaign and given to most pieces of inventory in Geopath’s system. Billups exposures are used in post-campaign attribution studies to see the results of a campaign. 

In determining the effectiveness of your campaign it’s important to understand the outcomes when the number of planned impressions and delivered exposures are different. 

Why are my Actual Exposures and Planned Impressions Different?

Exposures can be anywhere between 60% to 110% of the planned impressions. This can be due to a number of factors including:

  • Sheer over/under-delivery.
  • The qualification nature of scoring a view kicks out some impressions.
  • Inventory varies by publisher and there is some deviation in impression estimates.
  • Because impressions are the first value seen, they receive primary bias as a reliable metric.
  • Impressions are based on counts from Geopath based on predictions of what could happen in a market, whereas Billups Exposures indicate what actually did happen using data points from mobile devices.

In cases where exposures are higher than the impressions, it could be due to a number of factors. Maybe the weather was unusually nice for that time of year, or there was a special event. Impression information is collected from a specific data point. Any change in condition that would cause more or less people to be out and about than the data point can have an impact on how many actual exposures were yielded from the campaign.

Planning and Measuring Your Next Campaign with Billups

Billups uses patented software to determine how many exposures your advertisement had. We can help you to efficiently and intelligently plan your OOH campaigns and see verifiable results. Submit an RFP to get started today!

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