Triadic closure in two-mode networks: Redefining the global and local clustering coefficients

As the vast majority of network measures are defined for one-mode networks, two-mode networks often have to be projected onto one-mode networks to be analyzed. A number of issues arise in this transformation process, especially when analyzing ties among nodes’ contacts. For example, the values attained by the global and local clustering coefficients on projected random two-mode networks deviate from the expected values in corresponding classical one-mode networks. Moreover, both the local clustering coefficient and constraint (structural holes) are inversely associated to nodes’ two-mode degree. To overcome these issues, this paper proposes redefinitions of the clustering coefficients for two-mode networks.

► Projected two-mode networks have, by definition, high levels of clustering.
► The clustering coefficient and constraint (structural holes) are biased.
► Current two-mode clustering measures gauge reinforcement between two primary nodes.
► This paper reviews the origins of triangles and proposes measures using three nodes.
► The measures are applied to four empirical networks to highlight their applicability.