"One billion people have a Facebook account." " the average person on Earth does, in fact, use Facebook."

The population of the earth exceeds 7B (http://www.census.gov/population/popclockworld.html) so in fact the average person on Earth does not use facebook

*unless you live in a vacuum where 1/7 counts as half

You have to factor in the number of people who have regular internet access though.

I wouldn't be surprised if more than half of americans ages 18-24 have a facebook account but the original quote was:

"Stop living in a vacuum ... the average person on Earth does, in fact, use Facebook."

No qualifications made for internet access

Who cares about the qualification. Your entire premise is just ridiculous.

You can't just take your single data point (my close friends aren't on Facebook) and then extrapolate it (most people aren't on Facebook).

Pedantic correction: One billion people use their Facebook account every month. There are many more than that whose account is inactive, abandoned, or not used on a monthly basis.

pedantic correction: One billion Facebook accounts are accessed every month. No third party established that each account corresponds to a unique person.

Considering the vast amount of complaints towards Facebook regarding privacy concerns, do you really think it would be in the best interest of those users to allow third parties access to all of their data to "verify" that?

1B accounts != 1B sensate human beings. thats my point, and many people seem to conflate the two

no data to support, but I'm pretty sure the amount of people with multiple facebook accounts is pretty small(at least comparatively to things like e-mail adresses)