Clusters of nodes and subnets

In social network analysis (SNA), one of the key issues is to understand the structure of a network by identifying different groups (communities) within a larger set of nodes. After discussing concepts such as centrality (the importance of a node in the network) and structural holes (places that can be bridges between different groups), we move on to the analysis of clusters and subnetworks. Both concepts allow us to better understand how networks organize themselves into subgroups and how these groups affect the entire system.

A cluster is a group of nodes that are densely connected to each other but less connected to other nodes in the network. The distinguishing feature of clusters is their internal density of connections and differences in connections to nodes outside the cluster. This phenomenon is common in social networks, where we can observe the formation of smaller communities, such as groups of friends on social media, work teams in companies, or interest groups.

A subnetwork is any distinct part of a network that consists of a subset of nodes and the connections between them. A subnetwork can include nodes from different parts of the network, and its selection can be based on various criteria, such as topic, time, location, or type of relationship.

Clusters in social network analysis

Clusters are not only an interesting theoretical element, but also have a wide practical application in the analysis of social networks. The identification of clusters allows:

• Community detection: In social networks, clusters can represent groups that are more closely connected, such as Facebook friends, coworkers at a company, or people who share a common hobby.
• Information bubble analysis: People within a cluster can only share similar opinions and information, which leads to the formation of “information bubbles” in the network.
• Identifying leaders: Within a cluster, there are often high-profile individuals who act as opinion leaders or mediators between group members.
• To better understand what clusters and subnets are in social networks, below is a simplified network diagram with three highlighted clusters and a highlighted subnet.
  Rys.1 Clusters and subnetwork in social network.

 

• Each cluster (colored) is a set of nodes that are strongly connected to each other, representing a community.
• A subnet is a fragment of the network (gray nodes) that can be analyzed separately – e.g. as an area of ​​cooperation between clusters.
• Grey nodes often act as intermediaries, connecting different communities

Understanding clusters and subnetworks in social networks is key to understanding the structure of these networks. By analyzing clusters, we can better understand how people organize themselves into smaller groups, how they influence each other, and what roles individuals play within the overall network.