https://en.wikipedia.org/wiki/Marketing_mix_modeling https://en.wikipedia.org/wiki/Marketing_mix_modeling got big in the 1980s. It's always been pretty importan

https://en.wikipedia.org/wiki/Marketing_mix_modeling https://en.wikipedia.org/wiki/Marketing_mix_modeling got big in the 1980s. It's always been pretty important for marketers to know what channels work and what ones don't. Mail order ads used to list different PO Boxes so they could track sales attribution.