>> To measure the novelty of a paper, they rely on the notion that novelty is about combining pre-existing ideas in new and unexpected ways. They use the refere

>> To measure the novelty of a paper, they rely on the notion that novelty is about combining pre-existing ideas in new and unexpected ways. They use the references cited as a proxy for the sources of ideas that a paper grapples with, and look for papers that cite pairs of journals that have not previously been jointly cited. The 11.5% of papers with at least one pair of journals never previously cited together in the same paper are called “moderately” novel in their paper. "If I assign numbers to each of these things then it becomes data and I can do maths on it!" https://xkcd.com/2610 https://xkcd.com/2610 Also see: ad-hoc assumptions that become axioms of a theory without any attempt to justify them ("novelty is about combining pre-existing ideas in new and unexpected ways"... the Lego Brick Theory of Novelty, I presume).