"There is a science to advertising. Experienced advertisers have watched and recorded, tested and logged, and left records of countless campaigns. In these conditions the advertising and merchandising becomes a science. Principles are learned and proven by repeated tests” (Scientific Advertising).
This was written in 1923. And this was the beginning of the accountable marketing mindset.
In the 1920’s the careful attention to costs measurement of marketing effectiveness began. This mindset is alive and well today and we call it pipeline marketing.