Facebook's own statistics seem to suggest that students - particularly college students - are leaving the social network in droves. However, the reality might not be so simple.

When you set up an advert on the social networking site, you can choose how to target that ad, selecting certain demographics. Facebook will then tell you how many people that ad will reach, so sneaky statisticians have been mining data using that system for some time.

One company - iStrategyLabs - captured a set of data six months ago, and has just done the same thing again. College students are down 21.7%, and high school students are down 16.5%.

However, users who haven't specified an education level are up 134%, so it could just be that new users can't be bothered to type in the information.

The site's female bias is slowly shrinking. At the start of the year, 55.7% of users were female, and now it's 54.6%. Also interesting in the numbers is that the percentage of over-55s on the service has rocketed 513.7% since January, and that the largest group is 35-54 years old - 28.2%.

However, given the lack of any credible competition to Facebook's throne as the top social network, we wouldn't predict anyone defecting just yet, and that's a fact well understood by Facebook's board.

One of whom - Mark Andreessen - says that the social network's revenues could reach "billions" in five years - up from about 500 million now. "If they pushed the throttle forward on monetization they would be doing more than a billion this year", said Andreessen, founder of Netscape.