Laura Bocci

Clustering Large Data Set: An Applied Comparative Study

The aim of this paper is to analyze different strategies to cluster large data sets derived from social context. For the purpose of clustering, trials on effective and efficient methods for large databases have only been carried out in recent years due to the emergence of the field of data mining. In this paper a sequential approach based on multiobjective genetic algorithm as clustering technique is proposed. The proposed strategy is applied to a real-life data set consisting of approximately 1.5 million workers and the results are compared with those obtained by other methods to find out an unambiguous partitioning of data.

GINDCLUS: Generalized INDCLUS with External Information

A Generalized INDCLUS model, termed GINDCLUS, is presented for clustering three-way two-mode proximity data. In order to account for the heterogeneity of the data, both a partition of the subjects into homogeneous classes and a covering of the objects into groups are simultaneously determined. Furthermore, the availability of information which is external to the three-way data is exploited to better account for such heterogeneity: the weights of both classifications are linearly linked to external variables allowing for the identification of meaningful classes of subjects and groups of objects. The model is fitted in a least-squares framework, and an efficient Alternating Least-Squares algorithm is provided. An extensive simulation study and an application on benchmark data are also presented.