Glossary A–ZLetter V
Visibility adjustment
A visibility adjustment weights the number of people at a location by how likely they are actually to be able to see a particular advertising site.
It turns a footfall figure into an estimate of contacts with the advertisement. The value lies between zero and one.
The factor takes into account characteristics of the site and its location: size, height, distance and angle to the walking route, lighting, obstruction by other objects and competing advertising nearby. An example: 2,000 people pass along a platform in an hour; a screen facing across the walking direction is given a higher factor than one that hangs parallel to the route and can only be seen from the side. With screens, there is the added point that a creative plays for only part of the time.
Visibility adjustments are based on models and surveys, not on measuring every single glance. Different providers calculate with different assumptions, so impressions from two networks are only comparable if they were weighted in the same way. Operators should disclose whether and how such a factor was applied. A factor that is the same for every location does not describe any location accurately.