How can Google determine bounce rate if i don't have google analytics ?

Of course bounce rate is one of the hundred factors in the G algorithm.

What is, in your opinion, the way G uses to discover the bounce rate of a website if there is no google analytics script installed ?

Their toolbar installed on the users PC. You using AS.

And additionally some not-so-precise statistical analysis based on time before clicking on the next search result.

i would like to know that too

Monrox said:

Their toolbar installed on the users PC.

Click to expand...

This is a great answer, why didn't i think of that

Monrox said:

You using AS.

Click to expand...

This is not clear to me,
what do you mean ?

AS is an abbreviation for AdSense. Most abbreviated stuff in the internet marketing is not official but eventually it starts to make sense when you know the context.

Almost everything G is doing is based on their desire to track users. When you see a service from them there is a 99% chance that it can do (or more likely already doing) this. Chrome is often phoning home, same for Android, anything java/ flash based (such as Earth), their DNS service...

Google tracks every click in SERPs, so if a user clicks your link and then press the back button, it means that the exact same set of SERPs will load for that user again, and in Google's eyes, it's a bounce..

My experience is that a bounce rate of more than 80% over a few days, will kill your site in Google..