How Facebook Knows When Its Ads Influence Your Offline Purchases (opens in new tab)

...aaand facebook starts to buy news pieces to justify their ad network.

this is nothing more than a press-release for their atlas feature. A new low even for wired.

Some commentators in this discussion question why anyone would give their phone number to shops when they make a purchase. Yet millions of people give their mobile phone number (and name, date-of-birth and gender) to Google when they sign up for a Google account. And yet the degree of tracking that Google can undertake is an order of magnitude greater than what any individual store can track. Does Google use your mobile number solely for two-factor authentication and absolutely nothing else? Who knows? Google doesn't tell you.

When you can sign in on your tablet/mobile/desktop/TV/thermostat/fridge and who knows what else - how hard can it possibly be to stitch together your spending and consumption habits with all the other data collected about you? In fact, it wouldn't surprise me if those joined-up journeys have already been compiled. It's pretty obvious that the information companies collect about you goes far, far beyond creating a simple "advertising profile".

Companies like Google and Facebook (and others) have no self-restraint when it comes to tracking you and they don't even do it anonymously. How do they get away with it? Because we happily let them.

> The trick is that the hash of a phone number captured on Facebook will look just like the hash of the same phone number captured in a brick and mortar store, so the two companies can match the numbers without actually trading them.

This just isn't possible. How many cents would it cost to brute-force hash all legal American phone numbers?

I see false positives. So last week I decided to do my first project that will use a Raspberry Pi. I googled around to the pi site, amazon, newegg, (gasp) radio shack, microcenter, etc... I figured out what I wanted to get but didn't put anything in any carts. So then Pi ads start showing up on Facebook. IIRC a Radio Shack Pi ad too. Whatever. But now when I buy one, is Facebook going to claim some responsibility for the sale? Because they honestly don't deserve it. I'm going to buy one anyway and I have not seen an ad for a place I didn't look already. While I often give a real store the business based on "I can get it on the way home" the price difference in this case is nuts. So NewEgg it will be and Facebook ads aren't going to influence that.

In this case, correlation does not indicate causation.

"It has happened to you, and it has probably happened more than once."

Umm, no. Why on earth would I give my phone number or email address to random shops? This is crazy. I surely don't want merchants to contact me "about other stuff I might want to buy." This assumption sold as a certainty in this article is somewhat disturbing. Do others from the US feel the same way? (I'm from Germany. Different culture?)

"People voluntarily link things like phone numbers and email addresses to their Facebook accounts"

People voluntarily are idiots. Never connect a phone number to your FB account and use another mail address if you really need to have an account.

>As Boland explains it, Facebook simply shows advertisers that a given number of people who saw an ad for a product also purchased that product.

Facebook doesn't share my personalized shopping data with advertisers. That's good.

But the data still exists. So the data the advertisers receive is only really anonymous until there's some sort of security breach or economic decision whereby it's suddenly more profitable to sell the personalized data. Either or Both of which are inevitable.

All in all, a moderately informative marketing piece.

tldr; it doesn't, but offline vendors that collect your contact information they can anonymously check the proportion of purchasers which might [incidentally?] have been shown their ad on Facebook's network. Only a media buyer with a budget bigger than their brain would assume causality.

Who gives their phone number to store clerks? "Sorry, it's unlisted."

Is anyone else frightened the increasing efficiency of capitalism? Since when does user-experience depend on best fulfilling my consumer desires? Shouldn't I try to soften this impulse?

And this is why I did not give my phone number to facebook and why I use a different email for everything.

It's unfortunate that keeping one's privacy requires a lot of knowledge and work.

Amazon product pages already have Facebook tracker embedded, so Facebook knows what you are looking at. No need to provide your phone number.