Does playing tennis make you live 9.7 years longer?

Recently a post did the rounds on Twitter, claiming that people who play tennis live on average 9.7 years longer than people who play other sports. The figure comes from a recent analysis of people's exercise habits in Denmark. But not everyone on Twitter was convinced. Tennis is a sport that in many countries is expensive to play and so attracts wealthier players. Couldn't it be the players' socio-economic status driving the trend? We speak to medical statistician Adam Jacobs, to understand what the study in question can, and cannot, say for certain. If you see any stats that look too good to be true and want us to check them out, email moreorless@bbc.co.uk . Presenter: Tim Harford Producer: Lizzy McNeill Series Producer: Tom Colls Editor: Richard Vadon Production Coordinator: Siobhan Reed Sound Mix: James Beard.