Marketing Science

Marginal ROI vs ROI: Why efficiency beats revenue

Understanding why modern marketing optimization focuses on efficiency, not volume. Learn how marginal ROI transforms budget allocation and why the slope matters more than the height.

5 août 2025
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8 min de lecture

In marketing analytics, ROI (Return on Investment) is everywhere. It tells you how many euros you earned per euro spent. But when it comes to budget allocation and media optimization, the real game-changer is Marginal ROI (MROI) — the return on the next euro spent.

This simple shift from total to incremental perspective transforms how you evaluate and optimize your media mix.

But marketing response is not linear. Every channel eventually saturates — the more you spend, the smaller the incremental impact.

Where: - R = response (e.g., sales, conversions) - X = spend - K = half-saturation constant (spend level where response = 50% of max)

À propos de l'auteur

Cyril Noirot

Cyril Noirot

Lead Data Scientist

Data scientist freelance. Je conçois et déploie des systèmes de décision — prévision, pricing, marketing measurement, optimisation.

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