What is an MMM audit?

MMM = Marketing Mix Modelling

Marketing Mix Modelling estimates how advertising, price, promotion, and other factors drive outcomes such as sales or profit. Organisations use it to reallocate media budgets. When the model is fragile or misspecified, those reallocations can be confidently wrong.

As open-source stacks like Meridian, Robyn, and PyMC-Marketing, and AI-assisted / automated MMM products, have lowered the cost of producing a model, more brands run MMM in-house or through agencies. More of those models quietly shape seven- and eight-figure budgets.

Where AI and automation fall short

Automated pipelines can fit a model quickly. They cannot replace judgement on business question, identification, data quirks, or whether results agree with experiments. Dashboards look decisive; assumptions may not be. An audit is the human second opinion that tooling skips.

An audit is not a rebuild. It is a structured review: someone who did not build the model checks specification, data, assumptions, validation, and (optionally) calibration against experiments.

Who needs an MMM audit?

• Brand teams with an in-house model who want assurance before a major reallocation
• Consultancies providing assurance to a client on a third-party or internal MMM
• Agencies inviting a neutral review to strengthen credibility with the brand
• Finance / leadership who need a plain-English verdict on whether the model can be trusted

What does a good audit cover?

At minimum: identification and business question fit, prior and assumption choices, data coverage and leakage risks, adstock and saturation transforms, out-of-sample and sensitivity checks. Optionally: calibration against geo-lift or other incrementality tests, and reproduction of key results.

Read more about our process on how we audit, or browse the validation checklist guide.

What you walk away with

A written report with a clear verdict, issues ranked by severity, and specific fixes, not a vague “looks fine” or a sales pitch for a rebuild. Most findings can be addressed inside the current model; when a rebuild is the right call, we say so plainly.