Marketing Science

Michaelis-Menten equations in marketing mix modeling

Discover how the Michaelis-Menten equation models immediate diminishing returns in marketing. Learn when to use it instead of Hill functions and why it's the standard for direct response channels.

July 14, 2025
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10 min read

Marketing Mix Modeling relies on saturation curves to capture how marketing effectiveness changes with spend. While Hill functions offer flexibility through their shape parameter, the Michaelis-Menten equation provides a simpler, more interpretable model for channels that exhibit immediate diminishing returns.

Originally developed to describe enzyme kinetics in biochemistry, the Michaelis-Menten equation has become a fundamental tool in marketing analytics for modeling saturation effects without threshold behavior.

Where: - R is the response (e.g., conversions, sales) - X is the marketing spend - K is the half-saturation constant (spend level where response reaches 50% of maximum)

The Michaelis-Menten equation is actually a special case of the Hill function where n = 1. This makes it the simplest saturation model that still captures diminishing returns.

About the author

Cyril Noirot

Cyril Noirot

Lead Data Scientist

Freelance data scientist. I design and ship decision systems — forecasting, pricing, marketing measurement, optimization.

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