FACEBOOK draws real friends to trade shows like this one in London. Photo by Derzi Elekes Andor, released for public use.

This week, columnist Terry Gallagher is writing the OurValues series …

Does it ever strike you as odd that your friends have more friends than you?

Don’t worry about it. It’s perfectly normal. Mathematical in fact.

Now that a billion people around the world are using Facebook, we’re gathering a lot of data about friendship that previously was the province of survey researchers and academics. And that means that many people get to see for the first time that their friends have more friends than they do. That’s contrary to the impression most people have of their own popularity when they don’t have to look at the data.

A report from about a year ago found that the average Facebook user had 245 friends, but that the average friend on Facebook has 359 friends.

Wait a second. How can that add up?

It’s called “the friendship paradox,” a phenomenon first described by sociologist Scott Feld in 1991. It’s a form of sampling bias, they say, meaning people with more friends are more likely to be friends with you. People with few friends, for example? You’re not likely to be friends with them.

The friendship paradox is not a trivial observation. Among other things, it helps guide public health responses to epidemics by identifying central players in social groups.

(Here’s a corollary to the friendship paradox that you might not want to think about: it’s likely that your sexual partners have had more sexual partners than you.)

But how are you?

Are you more popular than your friends?

Ever experience friend envy on Facebook?

Originally published on OurValues.org.