Revenue is not the final commercial objective
A revenue-maximising allocation can favour products or customers with low margins, high returns or expensive fulfilment. If the business decision is about contribution, the valuation step must reflect those differences. An MMM output should not be labelled profit simply because media spend has been subtracted.
- Define contribution costs
- Translate incremental revenue
- Compare marginal value
- Stress-test the margin
The break-even guide defines the basic relationship. Agree with finance which costs are included in contribution and which remain outside the calculation.
A budget recommendation needs credible response estimates, consistent value assumptions and feasible constraints. The marketing budget decisions learning path connects this idea to the assumptions, practical checks and next steps.
To work through the connected decisions, read SaaS MMM: connect trial acquisition to retained value and CPG MMM: separate media lift from price and promotion.
Compare two illustrative channels
Suppose an additional £10,000 of spend is predicted to produce £40,000 of revenue in channel A and £30,000 in channel B. If the relevant contribution margins are 20% and 50%, contribution before advertising is £8,000 for A and £15,000 for B. After the extra media cost, the illustrative values are -£2,000 and £5,000.
Revenue ROAS ranks A higher, while this contribution calculation ranks B higher. The example assumes the revenue effects are incremental and the margins apply to the incremental customer or product mix. Those assumptions require evidence; the arithmetic cannot establish them.
Use the margin of the proposed change
An average company margin may not describe the customers reached by the next budget increment. Promotions, returns, shipping, payment costs and product mix can change with scale. Document the marginal value assumption rather than attaching the same historical average to every scenario.
If contribution is modelled directly as the outcome, avoid subtracting the same included costs twice. If revenue is modelled and converted afterwards, preserve a clear bridge from modelled revenue to contribution before and after advertising.
Stress-test before approving the allocation
Compare conservative, central and optimistic margin assumptions alongside response uncertainty. A recommendation that is attractive only under an optimistic margin deserves a limited test or better data. Use the allocation framework to keep the total, bounds and horizon consistent.
Price changes can affect both unit demand and contribution per unit. The elasticity guide helps separate those effects. Do not optimise a discount campaign using a full-price margin.
A useful decision memo states the incremental outcome, value conversion, included costs, uncertainty and the business action. After implementation, compare realised mix and costs with the assumptions. If the commercial bridge changed, update that bridge instead of attributing every difference to model error.
Sources and further practice
This article’s worked example is illustrative, not a measured client result. Use the linked methodology to check the assumptions before applying it.