One of the most important things that we need to do in the market is help educate people that the click is not really the most important metric for us. In fact now that we've been able to work with companies to look at in-store sales data, we find that of the people who saw a Facebook ad and then purchased the product in the store, 99% of them never clicked on an ad, so re-educating the market what the metrics are that are right for us.
That's from Sheryl Sandberg, COO of Facebook (you can get the transcript from Seeking Alpha). One might conclude that this was a bit of magician's misdirection (don't look at the hat, look at the pretty girl), or it might just be true. The efficacy of adverts has been studied pretty much forever. Ph.D. dissertations have been written.
Yahoo! has this to say:
For example, in their important paper on adfx, Abraham et. al (1990) open with the line, "Until recently, believing in the effectiveness of advertising and promotion was largely a matter of faith" -- a first sentence that might otherwise seem a bit peculiar given that before they penned it, approximately 4 trillion dollars had been spent on advertising.
If it's true that clicks really don't measure effectiveness, then what? Could the whole advert driven web go poof?
As postulated here more than once: an economy based on adverts is inherently unstable. While adverts are a useful adjunct to production, when adverts become what the economy produces? Real life becomes a version of Second Life (you may remember it?). "I'm sorry Dave. I'm afraid I can't do that."