Glossary A–ZLetter C
Contact frequency
Contact frequency states how often, on average, a person encounters an advert during a campaign.
It is calculated as the total number of impressions divided by the number of people reached. It complements reach, which states how many different people were reached.
Someone who walks past a screen in an underground station every day on the way to work will encounter a campaign many times over four weeks, while a tourist may see it once. If 100,000 impressions are counted among 25,000 different people, the average contact frequency is four. Planners control it through the number of sites, the frequency in the loop and the length of the flight.
Too few contacts let a message get lost, too many can become irritating. A cap per person, as is usual online, can hardly be applied to public screens, because the screen does not know who is standing in front of it. Operators should bear in mind that an average hides the distribution: a few commuters with a great many contacts can push it up considerably.