It isn’t news to say that Facebook is good for sharing content. Indeed, if this weekend’s debate is anything to go by, some people are coming to think the site promotes oversharing to an annoying degree.
But quite why the viral effect in Facebook is so strong has been difficult to understand in detail. In spite of its best efforts to nudge users towards looser privacy settings, navigating Facebook still feels like a set of small networks for friends rather than one large network.
A new study by Facebook and the University of Milan sheds some light on this.
The headline-grabbing finding is that the famous claim that everyone in the world is connected by “six degrees of separation” (itself based on some slightly shaky science) is in fact closer to five or even four on Facebook.
With Facebook now representing some 10 per cent of the world’s population, this is the largest study of its kind. (A study of Twitter, a much smaller site, last year also found that users were connected by only five degrees of separation.)
“While 99.6 per cent of all pairs of users are connected by paths with five degrees (six hops), 92 per cent are connected by only four degrees (five hops),” Facebook’s data team wrote in a blog post summarising the report.
As the research was conducted only on Facebook, it’s hard to credit the social network itself for shrinking the world. This sample obviously excludes areas such as China or sub-Saharan Africa where, for various reasons, Facebook is still little used.
But one surprising finding is that as the network has got larger, the number of “hops” connecting friends of friends has actually fallen – from 5.28 in 2008 to 4.74 today. The effect is stronger in the US, where more than half of the eligible population is actively using Facebook.
The aggressive virality – which has been found to have some surprising results on unsuspecting newspaper sites plugged into the new “open graph” – occurs even though 84 per cent of connections are within the same country and most people’s friends are of a similar age.
Facebook’s trick is that it is very nearly “fully connected”: 99.91 per cent of individuals on the site belong to a “single large connected component”.
That means any message posted on Facebook has the potential to reach almost everyone on the site, given enough links and shares. Just how content spreads is a topic for future study but as the authors conclude: “The world is even smaller than we expected.”
If nothing else, the research demonstrates that Facebook is prepared to use its horde of data to learn about the nature of humanity – as well as selling advertising.
