Table 1.
Theoretical definition of social network analysis indicators presented herein and their meaning in this study
| Indicator | Definition | Meaning in this study |
|---|---|---|
| Network size | ||
| Nodes | Actors within a network | Organisations in the co-authorship network |
| Links | Relationships or connections between actors | Co-authorship between organisations |
| Network connectivity/cohesion | ||
| Component | Subset of nodes in a network in which all of them are linked to each other, directly or indirectly | Group of organisations that were connected to one another through joint publications |
| Giant component | Largest component existing in the network | Largest group of organisations connected through joint publications; the larger the giant component size, or percentage of institutions included within it, the more interconnected the network is |
| Average degree | Average number of direct connections the network nodes have | Average number of collaborations per organisation; the higher the average degree, the more connected the network is |
| Average clustering coefficient | Measures the extent to which the nodes in the network establish a perfect cluster, in which all the nodes are interconnected | The extent of full connectivity between organisations; a high average clustering coefficient indicates that more institutions are interconnected within the network |
| Average path length | Average smallest number of connections that a node needs in order to reach any other in the network | The average distance between organisations; the lower the average path length, the more direct is the connection between organisations |
| Centrality/significance of nodes in the network | ||
| Degree centrality | Number of a node’s direct connections | A measure of how many direct contacts an organisation has Organisations with high degree centrality are usually focal points of communication in the network |
| Eigenvector centrality | Reflects the quantity and quality of the direct connections a node has | A measure of high connectivity and links to other highly connected organisations; higher values indicate influential organisations in the network |
| Betweeness centrality | Indicates to what extent a node acts as a “bridge” between the various other nodes in the network, which would otherwise be disconnected | A measure of how much an organisation mediates the connection between other institutions; an organisation with high betweeness centrality has the potential to control the flow of information in the network |
| Closeness centrality | Measures how close a node is to all other nodes in the network | A measure of the extent to which an organisation can directly reach others; organisations with high closeness centrality can quickly obtain and communicate information in the network |