← Glossary · Measurement & Metrics Measurement & Metrics Definition varies Attention Unit (AU) A cross-channel media-quality score that rates a placement’s likely attention, letting DOOH be compared with other channels on a single attention metric. A proprietary vendor metric, not an industry currency. Related terms Attention & Engagement The degree to which people focus on a message. Engagement rises with relevance, interactivity and the nature of exposure — captive audiences engage more than passing, non-captive ones. 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. 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. See also Research Attention as the new currencyAttention benchmarks across media