Table 1 Definitions of network indices
From: Social networks in primates: smart and tolerant species have more efficient networks
Network Index | Technical definition | Meaning | Instances |
|---|---|---|---|
Global Efficiency (E1) | Ratio between the number of individuals N and the number of connections I multiplied by the network diameter D (see equation 1) | How maximum individuals are connected with the minimum of connections | Values close to 1 indicate a minimum connection of nodes allowing optimal information transmission across a group |
Average Dyadic Efficiency (E2) | Inverse of the shortest path length d, for each pair of individuals i and j, within the network (see equation 2) | How well information can be efficiently transmitted to all individuals | Values close to 1 allow optimal information transmission across a group |
Centralisation index (CI) | Sum of the differences between each individual's centrality and the centrality of the most central individual, all divided by the sum of the differences of centralities under the hypothesis that the network was a star (see equation 3) | To what extent a network is dominated by a single or a few individuals | Values close to 0 indicate an equal or decentralised network whilst values close to 100 indicate a network centralised around one individual |
Modularity (Q) | Fraction of internal connections in each cluster minus the expected fraction if connections were distributed at random but with the same degree sequence | To what extent a group is clustered | Values close to 0 indicate a purely random distribution of relationships whilst values close to 1 indicate strong hierarchical clustering |
