In
sociology
Sociology is the scientific study of human society that focuses on society, human social behavior, patterns of Interpersonal ties, social relationships, social interaction, and aspects of culture associated with everyday life. The term sociol ...
, structural cohesion is the conception of a useful formal definition and measure of
cohesion in
social groups
In the social sciences, a social group is defined as two or more people who interact with one another, share similar characteristics, and collectively have a sense of unity. Regardless, social groups come in a myriad of sizes and varieties. Fo ...
. It is defined as the minimal number of actors in a
social network
A social network is a social structure consisting of a set of social actors (such as individuals or organizations), networks of Dyad (sociology), dyadic ties, and other Social relation, social interactions between actors. The social network per ...
that need to be removed to disconnect the group. It is thus identical to the question of the node
connectivity of a given
graph in
discrete mathematics
Discrete mathematics is the study of mathematical structures that can be considered "discrete" (in a way analogous to discrete variables, having a bijection with the set of natural numbers) rather than "continuous" (analogously to continuous f ...
. The vertex-cut version of
Menger's theorem also proves that the disconnection number is equivalent to a maximally sized group with a network in which every pair of persons has at least this number of separate paths between them. It is also useful to know that -cohesive graphs (or -components) are always a subgraph of a
-core, although a -core is not always -cohesive. A -core is simply a subgraph in which all nodes have at least neighbors but it need not even be connected.
The boundaries of
structural endogamy in a kinship group are a special case of structural cohesion.
Software
Cohesive.blockingis the R program for computing structural cohesion according to the Moody-White (2003)
algorithm
In mathematics and computer science, an algorithm () is a finite sequence of Rigour#Mathematics, mathematically rigorous instructions, typically used to solve a class of specific Computational problem, problems or to perform a computation. Algo ...
. This wiki site provides numerous examples and a tutorial for use with R.
Examples
Some illustrative examples are presented in the gallery below:
Image:RingNetwork.svg, The 6-node ring in the graph has connectivity-2 or a level 2 of structural cohesion because the removal of two nodes is needed to disconnect it.
Image:6n-graf.svg, The 6-node component (1-connected) has an embedded 2-component, nodes 1-5
Image:NetworkTopology-FullyConnected.png, A 6-node clique is a 5-component, structural cohesion 5
Perceived cohesion
Perceived Cohesion Scale (PCS) is a six item scale that is used to measure structural cohesion in groups. In 1990, Bollen and Hoyle used the PCS and applied it to a study of large groups which were used to assess the
psychometric qualities of their scale.
[Chin, Wynne W., et al]
Perceived Cohesion: A Conceptual and Empirical Examination: Adapting and Testing the Perceived Cohesion Scale in a Small-Group Setting.
1999. Small Group Research 30(6):751-766.
See also
*
Community cohesion
*
Social cohesion
*
Social network
A social network is a social structure consisting of a set of social actors (such as individuals or organizations), networks of Dyad (sociology), dyadic ties, and other Social relation, social interactions between actors. The social network per ...
References
{{Social networking
Social network analysis
Graph connectivity
Network analysis
Sociological terminology