Network Inference Using the Hub Model and Variants

Abstract

Statistical network analysis primarily focuses on inferring the parameters of an observed network. In many applications, especially in the social sciences, the observed data is the groups formed by individual subjects. In these applications, the network is itself a parameter of a statistical model. Zhao and Weko propose a model-based approach, called the hub model, to infer implicit networks from grouping behavior. The hub model assumes that each member of the group is brought together by a member of the group called the hub. The set of members which can serve as a hub is called the hub set. The hub model belongs to the family of Bernoulli mixture models. Identifiability of Bernoulli mixture model parameters is a notoriously difficult problem. This article proves identifiability of the hub model parameters and estimation consistency under mild conditions. Furthermore, this article generalizes the hub model by introducing a model component that allows hubless groups in which individual nodes spontaneously appear independent of any other individual. We refer to this additional component as the null component. The new model bridges the gap between the hub model and the degenerate case of the mixture model—the Bernoulli product. Identifiability and consistency are also proved for the new model. In addition, a penalized likelihood approach is proposed to estimate the hub set when it is unknown. Supplementary materials for this article are available online.

Keywords:

• Asymptotic properties
• Bernoulli mixture models
• Identifiability
• Model selection
• Network inference

Supplementary Materials

The supplementary materials contain proofs of all technical results in the article, additional numerical studies, and an analysis of extended bakery data.

Acknowledgments

The authors thank the editor, the associate editor, and two anonymous referees for their constructive feedback and suggestions.

Disclosure Statement

The authors report there are no competing interests to declare.

Notes

1 $|·|$ is the cardinality of a set.

2 Nodes v₁ and v₂ appear frequently so we include them in the potential hub set.

Additional information

Funding

Yunpeng Zhao acknowledges support from National Science Foundation grant DMS-1840203. Peter Bickel acknowledges support from National Science Foundation grant DMS-1713083. Dan Cheng and Zhibing He acknowledge support from National Science Foundation grant DMS-1902432 Simons Foundation Collaboration grant 854127.