Does Every Facebook User Spend 15 Hours a Month on the Site?

Facebook's metrics claim that people spend 700B minutes a month on the site -- if "people" means "active users," that's more than 15 hours a month for each of Facebook's 750M such users [ Nielsen found Americans spent 53B minutes on Facebook in May -- see our story ].

Facebook has defined an "active user" as someone who has logged on to the service within the past 30 days. By that definition a person who logs on to Facebook once a month is considered "active." Hmm.

By our calculation, those 750M active users need to spend 30 minutes a day, everyday, on Facebook, to get to 700B minutes.

Given those numbers and the propensity for some -- including us -- to remain logged on all day but not actively checking, are Facebook's "active user" and "time spent" statistics being inflated by a weak definition and obsessive users?

How much time on average do you spend a day on Facebook and of that, how much of that would you consider "active"?

Discuss in the comments.