This is incorrect. Companies do the experiments. They just don’t publish the results. Why would they? The idea that Amazon doesn’t know the ROI on their ad/marketing spend is laughable.
Because 50% of advertising spend is wasted, but it's hard to figure out which 50%.
If you're doing an $XY,000 ad campaign, it's a waste of your time and money to figure out which 50% it is.
If you're doing a $XY,000,000 ad campaign, you employ people whose job it is to figure out which 50% it is. The thing is, you usually don't go ahead and pay them to blog about it.
