A UK academic, Professor Daniel Miller of University College London, is leading an eight country, multi-city analysis of how Facebook is used, particularly among teenagers. His view is that the engine that drove Facebook forward, teen usage, is broken.

The study is called the Global Social Media Impact Study

Here is one big conclusion from it.

What we’ve learned from working with 16-18 year olds in the UK is that Facebook is not just on the slide, it is basically dead and buried. Mostly they feel embarrassed even to be associated with it. Where once parents worried about their children joining Facebook, the children now say it is their family that insists they stay there to post about their lives.

Teenagers are gravitating instead towards sites like Snapchat and Twitter, the former because interactions leave no permanent record, and the latter because it is so much easier to use. What’sApp and Instagram are also quoted by Miller (who acknowledges in his blog post on an academic website, The Conversation, that Instagram is owned by Facebook).

Teens don’t appear to be migrating away from Facebook as a statement against data gathering or privacy intrusions. The fact is, these alternatives are mobile-first apps and Facebook is still a web first platform. Even so, the share price had a great run this year.

Miller adds that young people are using alternative social networking sites for various reasons:

….the closest friends are connected to each other via Snapchat, WhatsApp is used to communicate with quite close friends and Twitter the wider friends. Instagram can include strangers and is used a little differently. Facebook, on the other hand, has become the link with older family, or even older siblings who have gone to university.

So by Miller’s own admission then Facebook is not dead and buried – it has been repositioned by one category of user. It’s important also to realize that the researchers on the study place the emphasis on change and diversity rather than decline, for Facebook.

The way people use social media differs hugely from place to place. These are ‘social’ media, intensely woven into the texture of our relationships. They lead us straight to intimate worlds of Chinese families split by internal migration, the new Brazilian middle class, cancer victims in London sharing the experience of terminal illness, Trinidadians stalking the latest scandal and much more.

But we can say two things for certain. We need to understand more about the diversity of usage within Facebook. We do tend to treat it as it were a homogeneous platform. And we can expect mobile to continue changing web usage habits in 2014, putting further pressure on Facebook just as its stock is beginning to fly.