Measurement & Metrics

Audience Impression

The canonical DOOH measurement unit: the total number of people with an opportunity to see (traffic), adjusted for notice and dwell time and calibrated to the spot length. The same concept the industry also calls Visibility Adjusted Contact (VAC).

Also known as: VAC, visibility adjusted contact

Source: IAB DOOH Glossary

Related terms

Opportunity to See The probability of being exposed to a medium’s content or advertising. OTS does not require actual exposure to all content — it counts the chance to see, not confirmed viewing. Impression A counted exposure of an ad to a person. In DOOH it is the foundational unit of currency, but the exact definition varies by standard — from a raw play, to an opportunity-to-see, to a viewability-qualified audience impression. Dwell Time How long a viewer remains in the zone from which a screen is visible. In beauty venues dwell time is exceptionally long — measured in tens of minutes — which is the core of beauty DOOH’s value. Viewable Impression An impression that met a viewability condition (the ad was actually on-screen and seeable). The relationship to VAC/audience impression is debated — some bodies treat viewable impressions as a bottom-up counterpart to VAC’s top-down approach.