Why true cross-media measurement remains a challenge?

A fragmented reality

Yannick Carriou began by framing the fundamental challenge: the fragmentation of media consumption. Audiences today move seamlessly across television, streaming platforms, social media, and other digital environments. But today’s audience measurement systems are still largely siloed, built for a time when media channels operated independently.

Traditional audience measurement, largely based on panels, can no longer capture this complexity and fragmented consumption on its own. “No panel at reasonable cost alone can give you all the answers,” he explained, pointing to the explosion of content and platforms. As a result, the industry is shifting toward hybrid models that combine panel data with large-scale platform data.

And this is only the beginning of the challenge.

Advertiser pressure

A major shift occurred in 2019 with the World Federation of Advertisers’ (WFA) “North Star” framework. For Carriou, this marked a turning point: “Advertisers demanded a customer-centric approach of cross-media measurement that reflects how campaigns are actually planned and executed. They called for transparency, comparability, and robust governance. This manifesto effectively set the agenda for the entire measurement industry.” Since then, all stakeholders have been working toward this vision.

A clash of cultures

According to Carriou, one of the key obstacles in developing cross-media measurement lies in the cultural divide between traditional media and digital platforms.

In Europe, measurement has historically been governed by Joint Industry Committees (JICs), which act as neutral arbiters. “These systems are built on transparency, collective agreement, and standardized methodologies. Measurement is treated as a shared “currency”, imperfect at times, but broadly accepted by all stakeholders”, explains Carriou.

Digital platforms, however, emerged from a very different context. Their metrics were initially not designed as industry standards, but as marketing tools. Platforms define their own measurement frameworks, control access to data, and prioritize competitive advantage over comparability. As Carriou put it, they “preferred to build competitive advantage over comparability”.

This divergence inevitably creates a fundamental tension. Cross-media measurement requires harmonization, but the largest players in the ecosystem operate on entirely different principles.

The legacy problem

Key obstacle in building cross-media measurement is the weight of history. Audience measurement systems have developed independently in each country over decades, resulting in deeply embedded local practices.

Even seemingly simple metrics like TV reach are calculated differently from one market to another. “These differences are not just technical, they are integrated into the entire media ecosystem, including planning tools, agency workflows, and trading models. Changing them would require a costly and complex transformation far beyond measurement itself.”

This explains why progress varies so widely across markets. As Carriou emphasized, “smaller countries like Belgium face the same technical and political challenges as larger ones, but with fewer resources. This makes initiatives like CIM ONE particularly ambitious… and particularly necessary.”

The biggest barrier: Data access

Despite this momentum, one challenge stands above all others: access to platform data.

To build a reliable cross-media system, measurement providers need detailed data from platforms such as YouTube, Netflix, and Meta. But these platforms operate within “walled gardens,” tightly controlling what data can be shared and how it can be used.

This leads to what Carriou described as a “permanent argument” between measurement bodies and platforms . Even when data is shared, it is often aggregated or restricted, limiting its usefulness for independent measurement and cross-platform comparisons.

Without meaningful access to this data, true cross-media measurement remains out of reach.

The metrics debate

A fundamental question remains: what should be measured, and how? Not all impressions are equal. A TV ad viewed in total on a large screen in a lean-back environment is not equivalent to a fleeting impression on social media. Yet cross-media systems require a common currency.

This has led to intense debates, particularly around standards such as those defined by the Media Rating Council (MRC). Broadcasters, in particular, argue that these standards do not fully capture the qualitative differences between media channels.

Reaching agreement on metrics is therefore not just a technical task, but a negotiation about value.

Lessons from France and a pragmatic outlook for Belgium

Carriou briefly shared insights from France, where Médiamétrie is developing a cross-media solution focused initially on video. The system combines multiple metrics (valid impressions, viewability, duration thresholds, reach, and frequency) across platforms.

However, even this advanced initiative has limitations. Not all platforms participate, and data gaps remain. The result is a “partial answer to the very legitimate needs of advertisers rather than a complete solution.”

This reinforces Carriou’s broader point: there is no perfect model to replicate. Each market must find its own path.

For Belgium, the message is both encouraging and sobering. CIM ONE is tackling the right problem, but expectations must be realistic. Cross-media measurement will not emerge overnight as a fully formed system. Instead, it will evolve incrementally, shaped by negotiation, compromise, and continuous improvement.

As Carriou concluded, “the journey toward cross-media measurement is not about finding a single solution, but about building a framework that works, imperfectly but effectively, for each market, and keeping it improve.”

In that sense, cross-media measurement is less a technological breakthrough than an ongoing industry dialogue.