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Comment by StevePerkins | Hacker News Reader

> "Instead, Google says its ad-buying tools will use new technologies it has been developing with others in what it calls a “privacy sandbox” to target ads without collecting information about individuals from multiple websites. One such technology analyzes users’ browsing habits on their own devices, and allows advertisers to target aggregated groups of users with similar interests, or “cohorts,” rather than individual users."

I'm having a hard time parsing this out, and seeing what's actually changed. How do they determine an individual's "cohort(s)", without collecting information about that individual across multiple websites?

Is it simply that the data is collected and processed client-side, rather than server-side? Would using a non-Chrome browser effectively opt-out altogether, then? I find this difficult to believe.

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The idea is that they group you with N other similar people where N is large enough to anonymise you enough to stop the worst complaints but small enough that advertisers still find it useful.

Some sort of principal component analysis to determine your "cohort".

An advertiser isn't that interested that you are you. They care that you are, for example, 55 with an interest in gardening and have been looking at lawnmower review sites.

So if I look up the specs on a pair of Bose QC-35's, I won't get internet-stalked with ads for that specific pair of headphones for the next 3 weeks whenever I pull up a weather report? But in stead I may see an uptick in general audiophile ads if I'm constantly reading articles about new gear that comes out? At least that sounds like a partial win in my book -- the first case was too creepy because it was so blatant. The second one may be worse because it is more subtle, but it creeps me out less for some reason. Kind of like how 2-3 decades ago when computer magazines were a thing, I kind of expected ads for computer parts in those magazines.

Edit: Actually, come to think about it, I wonder how people would have felt in the 80's if they got one of several editions of a newspaper based on magazines that they also subscribed to. Households that subscribed to fitness magazines would get a newspaper with more gym membership and weightlifting gear ads, and households that received woodworking magazines would have more Craftsman ads in their newspaper. Would people appreciate the customization of the paper, or would they see it as an invasion of privacy?

Unfortunately if enough people have been looking at Bose QC-35s then there's no reason why that couldn't be a fact about your cohort.

You may still be stalked about the Bose QC-35's. It really depends on how they create the "cohorts". The new design doesn't tell us their intent here. People who are interested in Bose QC-35's could be a "cohort" you are put into.

> if I look up the specs on a pair of Bose QC-35's, I won't get internet-stalked with ads for that specific pair of headphones for the next 3 weeks whenever I pull up a weather report

The WSJ seems to be describing https://github.com/WICG/floc, but the kind of remarketing you're describing is what https://github.com/WICG/turtledove is intended to support. Advertisers would still be able to run that kind of personalized ad, but the browser API would not allow them to learn your browsing history in the process.

(Disclosure: I work on ads and Google, speaking only for myself)

It's still bad. If you are in the X cohort and buy Y, the seller will know that you are in the X cohort if the seller targeted X, even if Y has nothing to do with X. This is the fundamental breach of privacy that Google can't get around.

To me, ads following you around the internet about a specific thing that you browsed is just an example of how the targeting ad system is broken. A better ad system would see that you were interested in specific item and then advertise other items that mesh nicely with the use of the specific item. If you bought A, then there's better chances you's be willing to spend money on B too.

"Owners of QC-35s" can easily be a cohort, especially since there's a lot of people in that group and it's easy hit the anonymization score required.

Or you can just use an effective ad blocker (I use uBlock Origin) and not see ads at all. IDK why everyone doesn't do this.

I thought this was how it already worked..

Here's Chrome's technical page for Privacy Sandbox: https://www.chromium.org/Home/chromium-privacy/privacy-sandb...

The bit you're quoting sounds like the WSJ trying to describe https://github.com/WICG/floc. That depends on the browser choosing to support the API, yes.

(Disclosure: I work on ads at Google, speaking only for myself)

This feels like some slight of hand targeting the current political and legal efforts looking into Google.

For example, if they aren't collecting information on you than how do they have enough information to create cohorts? Is it that they are deeming information processed on your local computer running their software something that isn't them collecting? This seems like a form of misdirection.

Without knowing the technical details (which one never knows with Google), it leave me the impression that they have moved some of their categorization software client side (Chrome, web workers, etc) and are saying that they aren't collecting the data in that case.

Is it Google using remote devices as edge devices to do a bunch of work they'd been doing server side?

This is probably related to the "ban" of third party cookies [1] and most likely they just found a way without using cookies but other technologies - most likely biometric features + Chrome data in case you're using Chrome

[1] https://www.cookiebot.com/en/google-third-party-cookies/

Edit: I did not have time to read it, but here is the paper and probably something like the algorithm they want to use: https://github.com/google/ads-privacy/blob/master/proposals/...

So now you, and your intellectual soulmates (whom you haven't met yet) will be targettable as a group. Hmm

A non-Chrome browser is always a good idea.

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