Digital out of home advertising has increased in popularity. From displays at bus stops to LED trucks to screens in local bars, digital out of home advertising is everywhere. The effectiveness of the advertising was usually measure through location ID technology provided by smart phone vendors. The DOOH ad provider used technology to detect the number of cell phones in the vicinity of the ad and — voila — the audience was measured. However, increased consumer privacy concerns have led many technology vendors to make location tracking and cross-app tracking an “opt in” or “opt out” function.  As more and more users “opt out” the value of this approach to audience measurement decreased.