[nl]

OK, so how is the success of that funnel measured vis-a-vis other promotional channels?

It's trivial easy to add a tracking id to this (in-fact I think it is on by default)

And are you able to demonstrate definitively that a visitor from FB concluded a sale? If so, how?

I think people are a little confused about if you are trolling or you genuinely don't know.

Anyway, https://developers.facebook.com/docs/facebook-pixel/pixel-wi... (and plenty of other methods)

It's really, really easy. And that is why Facebook and Google are printing money - vendors know it works and can measure exactly how well, so they throw money at them.

[nihonde]

FWIW, I am not trolling. FB domains are deliberately blocked via my hosts file, and my business has nothing to do with consumer ads. I am just a skeptic of intertuption advertising effectiveness in general, and curious to see how rigorous the defense of FB advertising will be. I am still not convinced that click tracking is effective, but I’m willing to be wrong.

[jaggederest]

It's effective enough to drive the entire marketing campaigns of multimillion-dollar businesses :)