As a data quality practitioner I have never been in doubt that when it is said that FaceBook has 900 million profiles, that doesn’t mean that 900 million people have a Facebook profile.
Some people have more than one profile. Some people who had a profile are not among us anymore. As reported by BBC in the article Facebook ‘likes’ and adverts’ value doubted, some profiles are fake resulting in FaceBook earning real money that should have been fake money.
Even some profiles are not really fake but serves other purposes like a snoopbook account created to reveal fraud.
And then some profiles belongs to (the owners of) real cats, as reported by James Standen in a comment to my post called Out of Facebook.
On another social media platform, Twitter, I am guilty of having 5 profiles. Besides my real account hlsdk I have created hldsk, hsldk and hlsdq, so I have been able to thank people mentioning me with a wrong spelled handle. And then there is my female side: MissDqPiggy.