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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Blockmodeling | 2/2 | https://en.wikipedia.org/wiki/Blockmodeling | reference | science, encyclopedia | 2026-05-05T15:46:57.060612+00:00 | kb-cron |
Among direct blockmodeling approaches are: structural equivalence and regular equivalence. Structural equivalence is a state, when units are connected to the rest of the network in an identical way(s), while regular equivalence occurs when units are equally related to equivalent others (units are not necessarily sharing neighbors, but have neighbour that are themselves similar).
Indirect blockmodeling approaches, where partitioning is dealt with as a traditional cluster analysis problem (measuring (dis)similarity results in a (dis)similarity matrix), are:
conventional blockmodeling, generalized blockmodeling: generalized blockmodeling of binary networks, generalized blockmodeling of valued networks and generalized homogeneity blockmodeling, prespecified blockmodeling. According to Brusco and Steinley (2011), the blockmodeling can be categorized (using a number of dimensions):
deterministic or stochastic blockmodeling, one–mode or two–mode networks, signed or unsigned networks, exploratory or confirmatory blockmodeling.
== Blockmodels == Blockmodels (sometimes also block models) are structures in which:
vertices (e.g., units, nodes) are assembled within a cluster, with each cluster identified as a vertex; from such vertices a graph can be constructed; combinations of all the links (ties), represented in a block as a single link between positions, while at the same time constructing one tie for each block. In a case, when there are no ties in a block, there will be no ties between the two positions that define the block. Computer programs can partition the social network according to pre-set conditions. When empirical blocks can be reasonably approximated in terms of ideal blocks, such blockmodels can be reduced to a blockimage, which is a representation of the original network, capturing its underlying 'functional anatomy'. Thus, blockmodels can "permit the data to characterize their own structure", and at the same time not seek to manifest a preconceived structure imposed by the researcher. Blockmodels can be created indirectly or directly, based on the construction of the criterion function. Indirect construction refers to a function, based on "compatible (dis)similarity measure between paris of units", while the direct construction is "a function measuring the fit of real blocks induced by a given clustering to the corresponding ideal blocks with perfect relations within each cluster and between clusters according to the considered types of connections (equivalence)".
=== Types === Blockmodels can be specified regarding the intuition, substance or the insight into the nature of the studied network; this can result in such models as follows:
parent-child role systems, organizational hierarchies, systems of ranked clusters,...
== Specialized programs == Blockmodeling is done with specialized computer programs, dedicated to the analysis of networks or blockmodeling in particular, as:
Pajek (Vladimir Batagelj and Andrej Mrvar), R–package Blockmodeling (Aleš Žiberna), Socnet.se: The blockmodeling console app (Win/Linux/Mac) (Carl Nordlund) StOCNET (Tom Snijders),... BLOCKS (Tom Snijders), CONCOR, Model and Model2 (Vladimir Batagelj),
== See also == Stochastic block model Mathematical sociology Role assignment Multiobjective blockmodeling Blockmodeling linked networks
== References ==