Modularity (Network Science)

Modularity is a single number that tells how strongly the connections in a network fall into tightly knit groups compared with what would be expected if links were placed at random. To compute it one imagines breaking the graph into clusters and then asks whether there are more links inside each cluster than a random wiring would produce; the excess of internal links is summed across all clusters, and the result is scaled so that higher values indicate clearer separation of groups.