In
sociology
Sociology is a social science that focuses on society, human social behavior, patterns of social relationships, social interaction, and aspects of culture associated with everyday life. It uses various methods of empirical investigation an ...
, structural cohesion is the conception of a useful formal definition and measure of
cohesion in
social groups. It is defined as the minimal number of actors in a
social network
A social network is a social structure made up of a set of social actors (such as individuals or organizations), sets of dyadic ties, and other social interactions between actors. The social network perspective provides a set of methods fo ...
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 continuou ...
. 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
''Structural endogamy'' is a network concept that provides a means of finding the boundaries of endogamy in a community, using simply the genealogical and marriage linkages. The concept is related to that of structural cohesion. The examples are ...
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 rigorous instructions, typically used to solve a class of specific problems or to perform a computation. Algorithms are used as specifications for performing ...
. 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
Community cohesion is a conceptual framework which attempts to measure the social relationships within a community. It relies on criteria such as: the presence of a shared vision, inclusion of those with diverse backgrounds, equal opportunity, and ...
*
Social cohesion
Group cohesiveness (also called group cohesion and social cohesion) arises when bonds link members of a social group to one another and to the group as a whole. Although cohesion is a multi-faceted process, it can be broken down into four main co ...
*
Social network
A social network is a social structure made up of a set of social actors (such as individuals or organizations), sets of dyadic ties, and other social interactions between actors. The social network perspective provides a set of methods fo ...
References
{{Social networking
Social network analysis
Graph connectivity
Network analysis
Sociological terminology