Applications of social network analysis in law enforcement
Source: Using Social Network Analysis to Profile Organised Crime (pdf download for article)
The article summarizes the pros and cons of social network analysis (SNA) over other, more simplistic methods, and considers its application to a case study. SNA involves mapping out relationships in a network before trying to apply definitions to the clusters and notable nodes that emerge as a result of the mapping. The result is a more in-depth analysis that provides insight into what nodes are central to a network, what nodes are not, and the various labels that can describe groups of nodes.
The case study considered analyzes the South African arms deal, specifically seeking to identify corruption within a network of defense contractors, bidders, companies, key individuals and various other parties. Application of SNA theory allowed researchers to map a network of all involved entities.
In the resulting network, we can see several key concepts at play. Just as directed networks can be used to model links between websites on the internet, it is used in this case to model various decision-making relationships between the entities in the arms deal. In the figure, node size is reflective of how essential a node is to the connectivity of the graph. This is based on the concept of local bridges: we can calculate how vital a node is by identifying all local bridges in the network, then ranking nodes based on how many bridges they are a part of.
The article discusses the concept of the prevalence of certain relationships in the network: the high percentage of relationships between businesses compared to relationships between individuals suggests that the majority of the corruption is on a corporate scale. Although this is not a concept we have discussed, it is interesting to see its applications in this case study.
Finally, we note that we could apply the scaled PageRank algorithm to this network to identify the relative power of the entities involved, allowing for identification of which corporations or individuals had the largest influence in the scenario.
The article, and the included case study provides an example of the analysis capabilities that network mapping can provide, and the kinds of insights into profiling that are possible in law enforcement.