How could anyone possibly know? You maintain spend because Facebook claims it's providing value. There's no way to actually know this with any certainty, and Facebook manipulating their figures doesn't add clarity in the least. That's why this whole issue is important — these people are spending millions on ads because of the numbers Facebook reports. Then people are spending millions more on stocks because of the profit generated by aforementioned hand waving.

Statistical measurement of lift in sales.

Most small advertisers wouldn't be able to do this, and attribution is hairy as hell, but the options for measuring this are there.

This is a bias of online thinking. Brick and mortar retail doesn't really know the conversion rate on ad spend. The old adage is that you are wasting half of your advertising spend, but the problem is that you never know which half.

So, we make decisions based on imperfect information. When it was TV or Radio ads, there were 3rd parties that measured the market and reach of the station. With Facebook, Youtube, etc we have to take their word for it.

You don't measure the conversion in case of a brick and mortar vendor. But you can still measure proxy values for effectiveness: an uptick in sales volume or number of clients after after starting a campaign, for example.

But we aren't just running one form of advertising at a time, so what to we attribute the uptick?

Also, our marketing doesn't exist in a vacuum. Weather, competitors, a traffic jam down the street, variations in employee performance, etc all impact the performance as well.

It's not like we can just A/B test Facebook video ads vs Pandora Ads and pick the winner.

So, we shift our budget based on the available information.

And the average video view length is part of the information that we used to make decisions.

I'm confused. you seem very confident that facebooks video marketing is a lie, even while you admit being unable to attribute sales.

I know multi-touch is hard, but doesn't that mean you should be less confident in your statements because the data is fuzzy?

He said that he used the avg view length on FB as a reason to choose that channel. If he had know that they didn't factor in <3 sec views he would perhaps not used that channel.