The marketing industry’s focus on deterministic measurement is restricting customer acquisition by misreading how consumers make decisions.

These were the thoughts of Tom Ridges, Founder and CEO of Herdify, who sat down with Joyti Rambhai, Affiliate Leaders Editor, who said marketers are over-relying on simple, trackable metrics.

He argued this leads to optimisation around the wrong targets, particularly customer acquisition cost (CAC), which prioritises volume over quality.

Ridges said: “We often stick to what can be measured easily. The issue isn’t measurement itself, but using simple concepts to understand a complex system.”

His alternative centres on network science and complexity theory, methods Herdify previously used to support government modelling during the pandemic. Applied to marketing, these tools track how behaviour spreads across groups, rather than focusing only on digital touchpoints.

Ridges stressed that offline influence is largely ignored in current models. Everyday exposure, such as seeing a product in a friend’s home, can act as “implied word of mouth” and influence decisions without direct interaction.

He pointed to affiliate marketing as a key example, describing it as “patient zero” due to its reliance on last-click attribution. This approach credits a single interaction while ignoring the wider journey behind a conversion.

Instead, Ridges highlighted behavioural “thresholds”, where consumers need multiple exposures across channels before taking action. These can include peer influence, advertising and broader brand visibility.

He called for a shift towards probabilistic models that reflect this complexity. By targeting areas where offline advocacy already exists and layering campaigns on top, marketers can improve performance.