Block model analysis

The block model analysis is a method for the simulation of relationship structures in a network, which is used in sociology.

It goes back to the group of Harvard structuralists around Harrison C. White . The procedure is inductive. Structural equivalences are the starting point for block model analyzes. Structurally equivalent are relationships that are comparable in their structure, i.e. have the same relationships between actors; z. B. A father's relationships with his three daughters are three structurally equivalent relationships. The block model analysis brings together different types of structural equivalence and thus allows extensive insights into the structures within a network.

method

A block model analysis basically requires four steps:

1. Data acquisition (for structural equivalence)
2. Block modeling
3. Block compaction
4. Block combination

Collection of the data (for structural equivalence) in a matrix

All relationships within a network are weighted using a value on a scale and stored in a matrix.
Example:
The sample data used is data that White himself uses: It concerns the relationships between 18 monastery novices. The novices were asked 8 questions to describe their relationship with the others:

• who they like
• whom they value
• who they consider to be the cause of controversy
• with whom they are enemies

and more.
They should award 3 points for the first choice, 2 points for the second choice and 1 point for the third choice. These values ​​are entered in a matrix:

Block model analysis step 1: data entry

Block modeling

This data is sorted in such a way that subgroups within the network can be identified. This software-based process is called "block modeling" and is the core of this method. White and his colleagues have developed algorithms for this purpose (the first was called the CONCOR algorithm) that rearrange the rows and columns of the matrix until a convincing block formation is obtained.
Example:
The sorted result of the monastery novices looks like this for the question "I like":

Block model analysis step 2: modeling

The block model analysis shows that there are essentially 3 subgroups that can be identified as blocks on the basis of the sympathy relation. It is also clear that the sympathy relationships between the groups are noticeably thin. Furthermore, based on the sympathy values, guesses can be made as to who occupies which positions within the subgroups. Person N2 receives the highest sympathy values ​​in the yellow group, while N14 has a special position, because although he expresses sympathy for group members, he does not receive any equivalent response.

Block compaction

In the next step, the data is compressed and reduced in order to arrive at more global statements. It is particularly important that there are numerous non-relations when determining structural equivalence.

Example:
In the present example, the subgroups and their sympathy relationships can be reduced to the fact that there are high sympathy values ​​within the respective groups, as well as expressions of sympathy that are directed from group C (red) to group B (yellow), but cannot be returned from there. This can be represented in a matrix as follows:

Block combination

In a final step, the compressed blocks can now be compared with one another for different structural equivalences. This enables a differentiated view of the internal dynamics of a network to be recognized.

Example:

In the present example, the compression of the blocks leads to the question "Who is the trouble spot?" To the following matrix:

To put it simply, group A (green) blames members of group B (yellow) and vice versa, and everyone agrees that group C (red) is where the troublemakers sit. In a specific case, this may not come as a great surprise, but it does open up new possibilities for interpretation, especially in the case of less similar questions.

The prognostic power of the block model analysis was shown in the specific case by the fact that the novice N2 was later expelled from the monastery (because of insubordination) and the novices N3, N17, N18 had to leave the monastery because of "immaturity".

Application example

In a study that has become famous, the rise of the Medici was researched with the help of block model analyzes. The credit and family relationships were mapped in matrices and analyzed using the block modeling method. (Padgett & Ansell, 1993)

classification

The block model analysis is still a very powerful tool. Above all, it is of great historical importance. Jansen describes "the development of ... block model analysis ... by the Harvard structuralists around Harrison C. White as the decisive advance that led to the establishment of network analysis as a separate field of research. ... With the block model analysis, they developed an algorithm that allows conclusions to be drawn from the relationship data on the level of the individual about position and role structures in society as a whole. ”(Jansen, 1999, p. 47)
Fuhse and Jansen complain about the low use of block model analysis ( Schmitt & Fuhse, 2015, p. 42, Jansen, 1999, p. 48). Clemens assigns the block model analysis to political field research (Clemens, 2015, p. 272). The block model analysis is certainly not so present because the algorithms have been significantly further developed and because the improved visualization options make it possible to view such data sets that go beyond the block model analysis in terms of their informative value.

Further development

So today a visualization using an algorithm by Yifan Hu, who z. B. is provided as part of the Gephi software , which map relationships within a network much better.

• The internal group formation becomes much better recognizable, especially in its delimitation and at the same time in its openness.
• Intermediate positions of individual individuals become much more clearly visible, since not every person is assigned to a group, but can be moved more or less close by the spatial positioning.
• The group-internal structures are easier to recognize through the strength of the edges.

literature

• I. Clemens: Educational Science as Cultural Science: The Potentials of Network Theory for a Cultural Studies and Cultural Theory Orientation of Educational Science. Edition Educational Science. Beltz Juventa, Weinheim 2015.
• R. Heidler: The block model analysis: theory and application of a network analysis method. Social science. German University Publishing House, Wiesbaden 2006.
• D. Jansen: Introduction to network analysis. VS Verlag für Sozialwissenschaften, 1999.
• JF Padgett, CK Ansell: Robust Action and the Rise of the Medici, 1400-1434. In: American Journal of Sociology. Volume 98, No. 6, 1993, pp. 1259-1319. doi: 10.1086 / 230190
• M. Schmitt, JA Fuhse: On the topicality of Harrison White: Introduction to his work: Current and classical social and cultural scientists. Springer VS, Wiesbaden 2015.
• HC White: Identity and Control. Princeton University Press, 2012.