Bayesian Rank-Clustering

TL;DR

This paper introduces a Bayesian rank-clustering model that groups objects with statistically indistinguishable ranks, effectively handling various ordinal data types and quantifying uncertainty, demonstrated on multiple real-world datasets.

Contribution

The paper proposes a novel Bayesian rank-clustering model using a spike-and-slab prior, addressing limitations of existing models in handling diverse data and uncertainty quantification.

Findings

Successfully applied to simulated data

Effective on survey, election, and sports data

Provides uncertainty estimates for rank clusters

Abstract

Traditional statistical inference on ordinal comparison data results in an overall ranking of objects, e.g., from best to worst, with each object having a unique rank. However, ranks of some objects may not be statistically distinguishable. This could happen due to insufficient data or to the true underlying object qualities being equal. Because uncertainty communication in estimates of overall rankings is notoriously difficult, we take a different approach and allow groups of objects to have equal ranks or be $\textit{rank-clustered}$ in our model. Existing models related to rank-clustering are limited by their inability to handle a variety of ordinal data types, to quantify uncertainty, or by the need to pre-specify the number and size of potential rank-clusters. We solve these limitations through our proposed Bayesian $\textit{Rank-Clustered Bradley-Terry-Luce}$ model. We accommodate rank-clustering via parameter fusion by imposing a novel spike-and-slab prior on object-specific worth parameters in Bradley-Terry-Luce family of distributions for ordinal comparisons. We demonstrate rank-clustering on simulated and real datasets in surveys, elections, and sports analytics.