[ratel]

I was really careful enough in my wording: Facebook sells privacy sensitive data as in very, very specific target groups for among other things ad targeting for their customers to use. I did not refer to the selling of private data.

[umanwizard]

I genuinely don’t understand the distinction you’re making.

Facebook does not make its money from “selling data” at all, whether “private data” or “privacy-sensitive data”.

[ghostpepper]

Not the OP, but I am guessing they are trying to say that the distinction between "you pay facebook and they give you a database full of private data" and "you pay facebook and they give you API access to a database of private data and allow you to query it in myriad ways leading to you creating your own database of highly accurate private data" is not as important a distinction as Facebook would have you believe. Or something along those lines.

[umanwizard]

But Facebook doesn’t let advertisers query their database of private data. I agree that if they did, it would not be very different from selling data, but they don’t.

[sasasassy]

But.. they do, though. You can (and people do) make a very targeted ad, then query what users matched with it, and so on until you've sufficient data for your purposes. Plus you can use their public APIs to then match their ad data with the users public information. Facebook knows this, and does not prevent it (by hiding user identifiers for instance) because it's part of their strategy.

[Voxoff]

Ah now this is sneaky. Is this widespread? Any sources?

[ambicapter]

Here's a guy targeting his roommate[0]. Previous discussion[1].

[0] https://ghostinfluence.com/the-ultimate-retaliation-pranking...

[1] https://news.ycombinator.com/item?id=8330931

[scarejunba]

By making a Custom Audience and then selectively uploading? I think you have to agree to not do this.

The audience size tricks like uploading an audience, then adding one to it and reuploading won’t work. There’s a cardinality fudging thing.

[ratel]

Dear umanwizard,

Genuinely not understanding something is fine. Already claiming someone was intellectually dishonest because you misread or misunderstood not so much.

The ads business of Facebook is based on the very specific data Facebook can provide their advertisers for very specific target audiences based on private information they gathered through their platform. Like ads for people who die their hair, have an affliction for cheese burgers, are right wing and live in zip code 20500. That is privacy sensitive information (although I picked a public person for this example). They do not provide customers with Trump's private number. That would be private data. They do not just sell ads on their platform, they sell specific target audiences on their platform.

[umanwizard]

> The ads business or Facebook is based on the very specific data Facebook can provide their advertisers

Again, no it isn’t. Facebook at no point provides data to its advertisers.

Yes, advertisers can say “show this ad to people who are right-wing and live in DC” (although I doubt “dyed hair” is a category). However, the advertisers are never provided with any data about who is in that category. That data never leaves Facebook.