Improving clustering stability with combinatorial MRFs

As clustering methods are often sensitive to parameter tuning, obtaining stability in clustering results is an important task. In this work, we aim at improving clustering stability by attempting to diminish the infiuence of algorithmic inconsistencies and enhance the signal that comes from the data. We propose a mechanism that takes m clusterings as input and outputs m clusterings of comparable quality, which are in higher agreement with each other. We call our method the Clustering Agreement Process (CAP). To preserve the clustering quality, CAP uses the same optimization procedure as used in clustering. In particular, we study the stability problem of randomized clustering methods (which usually produce different results at each run). We focus on methods that are based on inference in a combinatorial Markov Random Field (or Comraf, for short) of a simple topology. We instantiate CAP as inference within a more complex, bipartite Comraf. We test the resulting system on four datasets, three of which are medium-sized text collections, while the fourth is a large-scale user/movie dataset. First, in all the four cases, our system significantly improves the clustering stability measured in terms of the macro-averaged Jaccard index. Second, in all the four cases our system managed to significantly improve clustering quality as well, achieving the state-of-the-art results. Third, our system significantly improves stability of consensus clustering built on top of the randomized clustering solutions.