[downandout]

It appears that they do. From [1]:

When you visit a website that uses our advertising products (like AdSense), social products (like the +1 button), or analytics tools (Google Analytics), your web browser automatically sends certain information to Google....we may use the information we receive to, for example:

Make ads more effective....

[1] https://policies.google.com/privacy/partners

[cosmie]

In this case, the "may" part in there is relevant, and not just an attempt to add in ambiguity to defuse things.

The Google Analytics property owner has to explicitly opt-in to allow Google to do this. And part of that opt in includes the site owner agreeing to an addition ToS certifying that they both disclose they do so and have appropriate consent to do so. You can learn more about that at [1].

In practice, most site owners toggle this feature on without realizing the liability they've agreed to. Because it enables additional reports in GA (by merging and exposing the demographic targeting data their ad system has), as well as pushes GA data into Adwords and DoubleClick if you want to link your accounts. But, Google does keep the GA data siloed off by default.

[1] https://support.google.com/analytics/answer/2444872?hl=en

[downandout]

But the end result is that most GA widgets are reporting data that is being used by Google to improve ad targeting, since most site owners turn the feature on.

[anf]

[citation required] but even if true, getting site owners to opt-in to exchanging their user's privacy for psychographic and demographic correlations seems materially different than Facebook's "no opt out" on a relatively unrelated feature like a Like button on a 3rd party site. They used to and could again make the button work without using it to gather browsing data.