In
sociology
Sociology is a social science that focuses on society, human social behavior, patterns of Interpersonal ties, social relationships, social interaction, and aspects of culture associated with everyday life. It uses various methods of Empirical ...
, structural cohesion is the conception of a useful formal definition and measure of
cohesion in
social groups
In the social sciences, a social group can be 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 ...
. 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 for an ...
that need to be removed to disconnect the group. It is thus identical to the question of the node
connectivity
Connectivity may refer to:
Computing and technology
* Connectivity (media), the ability of the social media to accumulate economic capital from the users connections and activities
* Internet connectivity, the means by which individual terminals, ...
of a given
graph
Graph may refer to:
Mathematics
*Graph (discrete mathematics), a structure made of vertices and edges
**Graph theory, the study of such graphs and their properties
*Graph (topology), a topological space resembling a graph in the sense of discre ...
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
In the mathematical discipline of graph theory, Menger's theorem says that in a finite graph, the size of a minimum cut set is equal to the maximum number of disjoint paths that can be found between any pair of vertices.
Proved by Karl Menger in ...
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 Computational problem, problems or to perform a computation. Algorithms are used as specificat ...
. 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
Psychometrics is a field of study within psychology concerned with the theory and technique of measurement. Psychometrics generally refers to specialized fields within psychology and education devoted to testing, measurement, assessment, and ...
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 for an ...
References
{{Social networking
Social network analysis
Graph connectivity
Network analysis
Sociological terminology