I'm not sure if you're being intentionally obtuse or not. GA phones home with vast information about user, and builds a profile of them. That profile is correlated across sites to personalize search results and sell ads.
Please omit personal swipes from your HN comments. Your post would be fine without the first sentence.
Note this site guideline, including the last bit: "Please respond to the strongest plausible interpretation of what someone says, not a weaker one that's easier to criticize. Assume good faith."
I'm not being intentionally obtuse, but I also don't know all of Google's advertising business. I didn't think Google Analytics did that? What makes you think it does?
(GA sends a message to Google, but I had thought that it was not linked to your behavior on other sites via GA?)
Googe Analytics consultant here (not Google employee).
1. Google Analytics' primary identity signal is a first-party cookie. this is not shared between domains. There is no technical way to link identity between domains with different cookie values.
1a. Google Analytics has built-in library functions to allow site owners to share first-party cookie values between a whitelisted set of domains. This effectively lets one company with multiple sites share a first-party identifier, but still not let anyone (Google or otherwise) link that identity to identities set on other sites.
1b. BUT. But. BUT. Google is rolling out "Google Signals" for Google Analytics, which will use your Google Account as the identity signal instead for users who are logged in to Chrome. This, obviously, lets your identity be correlated across sites.
(Personally, I suspect that the availability of this feature played a part in Google's decision to let Chrome follow the industry towards blocking third-party cookies. But this is a baseless opinion, one step removed from a conspiracy theory.)
2. Google Analytics can link their identifier (the first-party cookie or Google Signals) to your DoubleClick profile via DoubleClick's third-party cookie. The checkbox that does this is unchecked by default. There are many other features of GA that encourage or require you to check this checkbox.
2a. Google's documentation (including legal contracts!) places limits in the data exchanged between the two profiles. Data exchanged does include demographic and interest information from DoubleClick's profile into GA. This is one of the big reasons why people click the checkbox.
To my knowledge, GA data is not used to inform the DoubleClick profile. GA data can be used to build an "audience" in various Google ad platforms, and direct ads to those people specifically, or to use as the basis for a "look-alike audience."
3. Google is a Processor under GDPR for Google Analytics, and a Controller under GDPR for Google Ads. To a first approximation, this means they make the specific legal claim that they do not use GA data for their own purposes. Linking Analytics and Ads data is... complicated and frankly I still haven't gotten an explanation of its legal status that I fully understand.
In my personal opinion, I don't think Google actually uses Google Analytics data. Most Analytics implementations are tire fires, and they can get all the data from other more reliable sources, like Publisher data or Chrome. Given that they have based on their entire GDPR compliance strategy for Analytics on being a Processor, I don't think the risk/reward is there.
(apologies for lack of copy-editing, the thunder's about to take my internet away)
Interesting insight. Their privacy policy suggests they are able to do this however[1]:
"When you’re not signed in to a Google Account, we store the information we collect with unique identifiers tied to the browser, application, or device you’re using."
What is stopping, legally, them from taking e.g. HTTP Headers from independent connections and linking them together through fingerprinting? Maybe this is not implemented in Google Analytics, but that is certainly not the only connection made to Google on most websites (see e.g. gstatic and Firebase). Since there is practically no technical barrier, it seems that the vague privacy policy leads to the only question being what the 'unique identifiers' are exactly.
Am I missing something, or does this not address the fact that https://whatsmybrowser.info/ will always yield the same thing whether a connection is made to GA, Firebase, YouTube or Blogger? That seems to have to do with connection timing and caching, not with what the connection itself leaks.
I thought the parent was talking about using information about the network connection to link users across sites hosted by the same entity?
If you're talking about fingerprinting in general, that is also something that all the browsers are working on. I'm most familiar with Chrome's strategy, which is to first switch APIs that provide a lot of entropy from something you get by default to something you have to actively request, figure out how to provide similar functionality more privately, and then enforce a privacy budget that does not allow collecting enough information to identify users: https://www.chromium.org/Home/chromium-privacy/privacy-sandb...
