What is marketing mix modelling and why is it coming back?
Marketing mix modelling (MMM) is a statistical technique estimating how different marketing activities contribute to sales, using aggregate historical data rather than tracking individuals.
How it works. A regression model relates sales over time to spend across channels, plus external factors — seasonality, pricing, promotions, competitor activity, weather, economic conditions. The output attributes a share of sales to each input, and estimates diminishing returns and carryover (the lasting effect of spend after it stops).
Crucially, it requires no user-level data at all. It works on weekly or monthly aggregates: spend by channel, sales, and context.
Why it is returning after decades out of fashion. MMM was the standard approach before digital tracking. It fell out of favour because click-level attribution appeared to offer precision MMM could not. Several things reversed that:
Tracking degraded. Third-party cookie restrictions, Apple's App Tracking Transparency, browser protections and consent requirements have substantially reduced the coverage and reliability of user-level attribution. The precise measurement turned out to be neither.
Privacy regulation makes aggregate methods legally simpler.
Attribution's blind spots became obvious. Click-based models cannot measure television, radio, out-of-home, sponsorship or the long-term effects of brand advertising — so they systematically credited the channels they could see. MMM measures everything that could plausibly affect sales.
Computing and open-source tools made it accessible to organisations that could never afford a consultancy engagement.
Its limitations are real:
It needs a lot of data — typically two or three years of history.
Correlation, not causation. Spend often rises when sales are expected to rise anyway, which biases results unless handled carefully.
It cannot optimise in-flight, reporting at aggregate cadence rather than daily.
Results are sensitive to specification, so two analysts can produce different answers.
The emerging consensus is a triangulation of MMM, incrementality experiments and attribution together.