Outdoor Digital Impressions – Divide by 8!

Gone are the days of DEC’s (Daily Effective Circulation). Using only traffic counts is no longer reliable. Also eradicated are Eyes On Impressions (EOI), which was the newer metric developed only a few short years ago. Today, advertisers and advertising agencies want more reliable data as to who is actually seeing their ads. The measurement system for Out-of-Home continues to advance… the result: TAB Out-of-Home Ratings.

With the growth expansion of Digital Displays, TAB (The OOH industry’s audience measurement organization) needed to develop a methodology for measuring digital units better. Up until recently, static unit EOI had been applied to digital displays. However, with digital displays, ads are only “flipped” within a one in 6 or a one in 8 rotation. Therefore, EOI numbers were greatly exaggerated, for they did not discount for this limited exposure. So, TAB had to find a way to not only measure audiences as they travel past displays, but they also had to determine audiences for ads as they rotate in time on thousands of digital structures.

TAB Out-of-Home Ratings ran a visibility study and came up with Visibility Adjustment Index (VIA). The Visibility Adjustment Index is a ratio or percentage of a unit’s total audience who are likely to notice the ad. The impact of common board characteristics, size, road side, distance from road, road type and illumination are all taken into consideration. In order to figure out the digital number of impressions for each spot, TAB uses the following measurement:

Let’s assume a digital board has a weekly circulation of 100,000 and that based on the vehicle’s speed of 30mph in the “contact zone” each driver has the opportunity to see 4 ad flips:
(Weekly Circulation * VIA * ad opportunities)/# of spots
Example: (100,000 * .60 * 4)/8 = 30,000 weekly impressions for each spot

That’s right, divide by 8. A board with a weekly circulation of 100,000 will have an Eyes On number of 60,000. Then multiply by 2 or 4 or 8, based on the vehicle spend and how many ad flips the driver has potential to see, then divide that number by 8 (the number of advertisers on each board).

This calculation provides a more accurate measurement of real viewed out-of-home impressions.

What does the future hold? A better way to measure out-of-home advertising.

Creative capabilities are seemingly endless when it comes to digital out-of-home. The future is constantly evolving as new technologies become available and more sophisticated. With these changes, we anticipate that TAB will bring more new ways to measure the effectiveness of this ever changing medium.

The Gillespie Group