Robust, reliable and accurate Out-of-Home (OOH) measurement sets the medium above the rest. In this three-part series, we delve into the nature of OOH audience measurement and why it works. Let’s begin with the how; discover the background and advanced techniques used in OOH audience measurement.

Growing expectations for accurate audience measurement 

Most media planners and buyers would agree that Out-of-Home (OOH) is the oldest medium, yet many are unaware that it is also one of the most accurately measured. Knowing this fact is ever more important in the modern media industry. These days, planners and buyers no longer want to buy media space, they want to buy audiences. Therefore, there is a growing demand for accurate audience measurement, especially considering the most recent debates on the accuracy of online advertising measurement. It is essential that all media provide accurate audience measurement data for planning, trading and evaluation of campaigns; in this respect OOH is ahead of the curve.

Sony digital OOH campaign in the urban centre of Brazil’s Sao Paolo.

Measuring up to global industry standards

Other than TV, OOH is the only medium to have established globally accepted standards for audience measurement. These standards have been sponsored by the global research organisation ESOMAR and endorsed by all major industry stakeholders* such as Wold Federation of Advertisers (WFA), The European Association of Communications Agencies (EACA) and the 4As. The OOH guidelines have set common ground for both international and local best practice and research standards.

Real contact vs potential contact

Unlike most other media, which provide measurement based on viewable impressions, the best OOH audience measurement programs deliver actual viewed impressions. In a world where most media deliver measurement based only on potential contact, OOH figures give the number of people who saw your ad (VAC) rather than the number of who could have seen it (OTC). 

Pioneering Big Data

OOH pioneered the use of Big Data over twenty years ago, before it came on the radar of mainstream advertising conversations. Since the 1990s, the industry has been using a system that integrated large data sets with dedicated surveys and a refined definition of ‘contact’ at an individual panel level to deliver a precise viewership for campaigns.

How does OOH measure its audiences?

You can think of OOH audience measurement as being built on four main independent blocks of data, each overlaid and integrated with the other creating Big Data. Let’s look at each of these four building blocks.

Identifying patterns: The Travel Survey

To identify audiences, we must first understand where, when and how people move around the city. In OOH measurement systems around the world, a detailed travel survey based on a representative population is conducted to identify detailed patterns of consumer mobility.

These surveys can be memory based but in most cases, they involve passive sensing and recording of the participants’ movements via a smartphone or a custom device that measures GPS and Wi-Fi signals. These devices can even incorporate accelerometers, barometers and compasses to establish everything from the mode of transport and the routes a person takes, right down to the granularity of the floor of buildings he or she visits.

OOH Audience Measurement 101: Identifying Patterns of Movement with a Travel Survey

Identifying Traffic: Vehicular Data

To comprehensively measure traffic going past the panels, OOH audience measurement systems integrate the results from the consumer Travel Surveys with big data sets of traffic flows around the city.

This data includes information on every mode of traffic and come from a variety of sources including official government traffic counts, transport authorities, GPS, real time sensors on panels, video counting techniques and even satellite spectrum imaging.

OOH Audience Measurement 101: Identifying Traffic movement and density with Vehicular Data

Identifying Ads: Panel Classification and Mapping

Not all panels are physically the same, therefore their visibility must be weighted differently within the audience measurement system.

When the full catalogue of advertising panels is imported into the system, every panel is classified by its physical characteristics such as size, height from the ground, angle to the road and illumination. Each panel is then geolocated and placed accordingly on the same map used by the traffic data sets . The resulting clasification establishes which of the pedestrian and vehicular traffic will result in potential views for that panel.

OOH Audience Measurement 101: Identifying Ad visbility with Panel Classification

Analysing Views: Visibility Adjusted Contacts (VAC’s)

Once we have the potential audience numbers for a panel, how can you be sure that people have seen it?

Advanced OOH measurement systems incorporate algorithms built around extensive eye movement research based on established psychological techniques on how people view and respond to the world around them. By analysing all classification factors for panels and audience behaviour in this way, these measurement systems can convert the number of viewable impressions (OTCs) into actual viewed impressions (VACs). It is the application of VACs that makes the accuracy of OOH audience measurement unparalleled within the media measurement landscape.

OOH Audience Measurement 101: Analysing Actual Views by applying Visibility Adjusted Contacts (VACs)

Want to find out more about VAC’s? Discover a study on

eye-tracking of visibility hit rates. Meanwhile, stay tuned for our second instalment in this OOH Audience Measurement Series where we will compare audience measurement systems across the media landscape to offer you a comprehensive overview of their performance medium to medium.

Resources*

Global Guidelines on Out-of-Home Audience Measurement
ESOMAR: Global data, research and insights
WFA: World Federation of Advertisers
EACA: European Association of Communications Agencies
4As: the national trade association to represent U.S. advertising agencies
Postar Visibility Research: An integrative eye-tracking study of visibility hit rates

for poster panels in UK environments