Community detection in bipartite signed networks is highly dependent on parameter choice

TL;DR

This paper evaluates community detection methods in bipartite signed networks, highlighting their sensitivity to parameter choices and the risk of identifying spurious communities without proper validation.

Contribution

It systematically assesses the effectiveness of community detection algorithms on bipartite signed networks using synthetic and real data, revealing their dependence on parameter tuning.

Findings

Methods often detect spurious communities when no true communities exist.

Performance improves when actual communities are present, but is highly sensitive to parameters.

Researchers should validate community detection results with robustness checks or external data.

Abstract

Decision-making processes often involve voting. Human interactions with exogenous entities such as legislations or products can be effectively modeled as two-mode (bipartite) signed networks-where people can either vote positively, negatively, or abstain from voting on the entities. Detecting communities in such networks could help us understand underlying properties: for example ideological camps or consumer preferences. While community detection is an established practice separately for bipartite and signed networks, it remains largely unexplored in the case of bipartite signed networks. In this paper, we systematically evaluate the efficacy of community detection methods on projected bipartite signed networks using a synthetic benchmark and real-world datasets. Our findings reveal that when no communities are present in the data, these methods often recover spurious user communities. When communities are present, the algorithms exhibit promising performance, although their performance is highly susceptible to parameter choice. This indicates that researchers using community detection methods in the context of bipartite signed networks should not take the communities found at face value: it is essential to assess the robustness of parameter choices or perform domain-specific external validation.