Ranking indirect connections in literature‐based discovery: The role of medical subject headings

Arrowsmith, a computer‐assisted process for literature‐based discovery, takes as input two disjoint sets of records (A, C) from the Medline database. It produces a list of title words and phrases, B, that are common to A and C, and displays the title context in which each B‐term occurs within A and within C. Subject experts then can try to find A–B and B–C title‐pairs that together may suggest novel and plausible indirect A–C relationships (via B‐terms) that are of particular interest in the absence of any known direct A–C relationship. The list of B‐terms typically is so large that it is difficult to find the relatively few that contribute to scientifically interesting connections. The purpose of the present article is to propose and test several techniques for improving the quality of the B‐list. These techniques exploit the Medical Subject Headings (MeSH) that are assigned to each input record. A MesH‐based concept of literature cohesiveness is defined and plays a key role. The proposed techniques are tested on a published example of indirect connections between migraine and magnesium deficiency. The tests demonstrate how the earlier results can be replicated with a more efficient and more systematic computer‐aided process.