If you’re freezing coefficients in your media mix model, your model is broken. It’s one of the most common, and damaging, shortcuts in MMM. Something looks off in your results, so instead of investigating the cause, someone manually locks in a coefficient they “trust” and reruns the model until things look more reasonable. But the whole point of having a model is to let it tell you the results, not the other way around. In this article, we’ll walk through: Exactly why freezing coefficients undermines the integrity of your MMM. How this practice introduces hidden bias. What you should be doing instead to build stability and trust in your model results. Frozen Coefficients Are Lies No one—not your vendor, not…