Six degrees of separation: the small world of medical education

Conventional wisdom has it that everyone on earth is on average only six steps away from knowing any other person through 'a friend of a friend'. On a local level, however, many people experience that most of their acquaintances know each other. It is thus hard to imagine how such a highly clustered group could be so well connected to the rest of the world. In this paper, we investigate how co-authorship connects scholars in medical education and whether the six degrees of separation hypothesis also applies to the network of authors in the field.

We constructed a mathematical graph from publication data obtained on the top three journals in the field and analysed it using social network analysis methods. We found Lorelei Lingard to be one centre of the network of co-authors and determined the numbers of authors who were one, two or more steps away from her. We further created a website that makes it possible to identify the shortest path from any author in the field to any other, including links to the connecting papers.

The analysis covered 16 653 papers by a total of 24 258 different authors. Co-authorship connected authors into 68 663 unique pairs, of which 61 937 had co-authored only one article; 67.43% of all authors were linked to each other through a 'co-author of a co-author'. The average shortest path between any two authors in this network was 5.98 (min 1, max 17); the average distance to Lorelei Lingard was 4.17 (min 1, max 10).

The field of medical education represents what social network analysts term 'a small world network'. Making the connections between its actors visible may provide a new perspective on social phenomena that occur in this world, including peer review, citation and conference invitations.