Most of us have wondered at some point whether our teenager has enough friends, or the right ones. We usually go on surface stuff, who they mention, who they see at the weekend, whether they seem to be in the thick of things or a bit off to the side. As parents it is really interesting to understand how researchers actually study this. They essentially go into schools and ask a whole year group to name their friends. Then they put all the answers together and look at the year as a whole. It gives them a kind of map of the social world of that year, showing who is in the middle of things, who is out at the edge, who is on their own, and how the different groups do or do not join up. The method is called social network analysis. What the map shows is fascinating. As parents we sometimes worry about whether our teenager is well liked or high up in the pecking order. But the thing that seems to matter for how a young person is doing is not status. It is whether they have a couple...