I wish they showed how many people weren't using Private Browsing. For all we know the spikes might just be because more people are browsing the internet at those times (I suspect that's the lunch spike).

In the context of this discussion, percentage of Private Browsing activations would be more useful.

This is a great point, and one we should have addressed in the post.

That said, there is not generally a spike in usage at lunch for anything else. For many other metrics of interest we see a familiar sinusoidal wave of usage, with the low point at around 3 or 4am, and a high point at approximately 6-7pm.

Thus the spike in usage at lunch turns out to be quite unexpected.

Apart from understanding how much time people spend in private browsing, here's a recent paper that talks about the technical details of private browsing mode of popular browsers (Firefox, IE, Chrome and Safari).

http://www.usenix.org/events/sec10/tech/full_papers/Aggarwal...

Internet Explorer private browsing is fantastic (the only technical advantage over competition left IMHO). Starting new private windows doesn't close the existing tabs. One can have many private windows, each with separate cookies. So logging in say google mail (or HN) with 15 different accounts at the same time is not a problem.

Same exact thing in Opera. Private browsing is per-tab, cookies are separate per private tab (so multiple accounts into gmail is okay). You can open private tabs right next to regular, they don't live in another window (as Chrome enforces).

What version of IE are you talking about?

8.0

Thanks, this is what I assumed I'd be getting from the original link.

Amazing that people are able to find what they want to see but don't want others to know that they wanted to see and be done seeing whatever they saw in as little on average as 10 minutes of time.

I rather enjoyed Mike's comment on the blog itself

Googling 'anniversary present ideas' and then buying the present shouldn't take more than 10 minutes.

It looks like it could be providing a false sense of security for people at work, despite the warning that Firefox gives the user about the employer and ISP still being able to track what he's doing. Are people really reading that warning and understanding what it means?

Exactly. I've known very few companies (of size) where the history/cache/whatever of your local browser is of any importance. It's all logged and analyzed at the border.

So I guess we now have empirical evidence of how long the average person's masturbation session is.

Why are web browsers reporting this information back to Mozilla in the first place?

It's a voluntary study: https://testpilot.mozillalabs.com/testcases/aweeklife