"I'm not going to share my advertising accounts with you; I'm just going to ask you to trust that when I get my laptop out and show my results to my 'marketing skeptical' friends, they stop being skeptical."
I'm not publishing a paper in the comments. This is HN. Regardless, you cherry picked one aspect of my comment, and it's very hard from my perspective to see that it was done in good faith.
I'd like to be proven otherwise, so, here are my key points, which you didn't contend with:
-> It's possible to completely isolate the effect of advertising spend, thereby making the effectiveness (or not) measurable.
-> I pointed to growing revenues on Google/FB's platforms, two platforms which make isolated measurement feasible.
In terms of _externally_ verifiable facts, that's the best I'll be able to give you.
The rest, you (and others) have to take on a/ good faith b/ using basic logic, that I'm telling the truth.
spoken like a true used car salesman