Fewer than half of brands have a defined effectiveness function

Fewer than half of brands treat marketing effectiveness as a properly defined function with someone clearly accountable for it.

That figure, 46.1%, comes from The Language of Effectiveness 2026, Marketing Week’s annual study run in partnership with Kantar and Google. The sample is 630 brand-side marketers. It is not a survey of agencies or consultants telling clients what they need: it is clients describing their own set-up.

The split by business type is the sharper number. Among B2C marketers, 56.7% say they work somewhere with a well-defined, fully accountable effectiveness function. Among their B2B peers it is 29.1%. Two thirds of the sample, 67.6%, take the view that effectiveness is everybody’s responsibility rather than a dedicated team’s, which is a fine principle and a familiar route to nobody owning it.

The supporting findings reported by Marketing Week point the same way. Just 35.2% are satisfied with the analytics available to judge their creative work. Only 44.9% work regularly with finance on effectiveness analysis. And 22.7% admit they do not always understand how campaign analysis connects to the decisions their organisation then makes about marketing.

The timing is awkward. Budgets are being defended on evidence more than at any point in the last decade, and the research describes an industry where the evidence function is often improvised. Naming an owner, agreeing what counts as proof before the campaign runs, and having finance in the room are unglamorous fixes, but they are the difference between a number that survives contact with a CFO and one that does not. It is the same discipline behind how we score work here: decide the criteria first, then mark against them.