Bayesian modelling and computation utilising directed cycles in multiple network data

TL;DR

This paper introduces a new Bayesian network model that explicitly incorporates cycles, using a novel distance metric and computational framework, to better analyze ecological networks with complex motifs.

Contribution

It develops a novel cycle-focused network distance metric and integrates it into the SNF model, enabling explicit inference on network cycles in ecological data.

Findings

Model captures cycle behavior in ecological networks

Improves inference over existing models that ignore cycles

Demonstrates effectiveness on fish interaction data

Abstract

Modelling multiple network data is crucial for addressing a wide range of applied research questions. However, there are many challenges, both theoretical and computational, to address. Network cycles are often of particular interest in many applications; for example in ecology a largely unexplored area has been how to incorporate network cycles within the inferential framework in an explicit way. The recently developed Spherical Network Family of models (SNF) offers a flexible formulation for modelling multiple network data that permits any type of metric. This has opened up the possibility to formulate network models that focus on network properties hitherto not possible or practical to consider. In this article we propose a novel network distance metric that measures similarities between networks with respect to their cycles, and incorporates this within the SNF model to allow inferences that explicitly capture information on cycles. These network motifs are of particular interest in ecological studies aimed at understanding competitive and hierarchical interactions. We further propose a novel computational framework to allow posterior inferences from the intractable SNF model for moderate-sized networks. Lastly, we apply the resulting methodology to a set of ecological network data studying aggressive interactions between species of fish. We show our model is able to make cogent inferences concerning the cycle behaviour amongst the species, and beyond those possible from a model that does not consider this network motif.