A Marketing Mix Model is not complete when code runs and forecast appears acceptable.
A Marketing Mix Model is not complete when code runs and forecast appears acceptable. It becomes a decision system with an owner, authorised use, limits, independent validation, monitoring and withdrawal procedure. Control intensity depends on financial exposure, uncertainty, frequency and reversibility. An exploratory model and a monthly reallocation engine cannot share the same approval level.
Decision and method.
Authorise MMM use by calculated risk tier, with controls and limits proportionate to exposure and ability to correct the decision. Inventory version, owner, developer, data, objectives, uses, users, dependencies, assumptions, validation date and influenced decisions. Score financial exposure, uncertainty, frequency and reversibility with common criteria; the tier sets independence, test depth and approval authority. Require data review, technical validation, reference comparison, sensitivity test and business approval before use; retain reservations and limits in outputs. Compare recommendations, actual decisions and results; trigger review after material change, drift, experimental discrepancy or exposure breach.
Worked example.
An MMM proposes moving €800,000. Exposure scores 3 out of 4, uncertainty 4 because iROAS ranges from 0.8 to 2.6, and reversibility 2 because budget is reviewed monthly. Weights are 40%, 40% and 20%. Risk score: 3 × 0.4 + 4 × 0.4 + 2 × 0.2 = 3.2 out of 4, high tier. The rule requires independent validation, sensitivity, experimental comparison and a 20% pilot: 800,000 × 20% = €160,000. Full move is not authorised; expansion requires pilot results within approved range.
Checks and limits.
Each version has owner, authorised uses and limits; control rises with exposure, uncertainty and irreversibility; high-risk use requires independent challenge; drift, experimental discrepancy and material change trigger review. This grid is not a marketing regulatory standard. Good governance does not repair a conceptually weak model. Risk score does not replace documented committee judgement.
Resources and sources.
Download the MMM governance register. Related: validate the model, calibrate with experiments, decide under uncertainty. Sources: Board of Governors, OCC and FDIC (2026); Chan and Perry (2017); Zhang et al. (2024).