Human Cluster Evaluation and Formal Quality Measures: A Comparative Study

Clustering quality evaluation is an essential component of cluster analysis. Given the plethora of clustering techniques and their possible parameter settings, data analysts require sound means of comparing alternate partitions of the same data. When proposing a novel technique, researchers commonly apply two means of clustering quality evaluation. First, they apply formal Clustering Quality Measures (CQMs) to compare the results of the novel technique with those of previous algorithms. Second, they visually present the resultant partitions of the novel method and invite readers to see for themselves that it uncovers the correct partition. These two approaches are viewed as disjoint and complementary. Our study compares formal CQMs with human evaluations using a diverse set of measures based on a novel theoretical taxonomy. We find that some highly natural CQMs are in sharp contrast with human evaluations while others correlate well. Through a comparison of clustering experts and novices, as well as a consistency analysis, we support the hypothesis that clustering evaluation skill is present in the general population.