Topics as Clusters of Citation Links to Highly Cited Sources: The Case of Research on International Relations

TL;DR

This paper introduces a novel bibliometric clustering method focusing on citation links to highly cited sources to identify research topics in International Relations, revealing overlapping and cohesive thematic clusters.

Contribution

It proposes a new link clustering approach restricted to highly cited sources, using a local memetic algorithm to identify overlapping research topics.

Findings

Clusters are well separated from the network

Overlapping clusters reveal complex research front structures

Cohesive cores of topics are identified within clusters

Abstract

Following Henry Small in his approach to co-citation analysis, highly cited sources are seen as concept symbols of research fronts. But instead of co-cited sources I cluster citation links, which are the thematically least heterogenous elements in bibliometric studies. To obtain clusters representing topics characterised by concepts I restrict link clustering to citation links to highly cited sources. Clusters of citation links between papers in a political-science subfield (International Relations) and 300 of their sources most cited in the period 2006-2015 are constructed by a local memetic algorithm. It finds local minima in a cost landscape corresponding to clusters, which can overlap each other pervasively. The clusters obtained are well separated from the rest of the network but can have suboptimal cohesion. Cohesive cores of topics are found by applying an algorithm that constructs core-periphery structures in link sets. In this methodological paper I only discuss some first clustering results for the second half of the 10-years period.