A mixture model for the classification of three-way proximity data

  • Authors:
  • Laura Bocci;Donatella Vicari;Maurizio Vichi

  • Affiliations:
  • Department of Sociology and Communications, University of Rome "La Sapienza", v. Salaria, 113, I-00198 Rome, Italy;Department of Statistics, Probability and Applied Statistics, University of Rome "La Sapienza", Pl. Aldo Moro, 5, I-00185 Rome, Italy;Department of Statistics, Probability and Applied Statistics, University of Rome "La Sapienza", Pl. Aldo Moro, 5, I-00185 Rome, Italy

  • Venue:
  • Computational Statistics & Data Analysis
  • Year:
  • 2006

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Abstract

Large data sets organized into a three-way proximity array are generally difficult to comprehend and specific techniques are necessary to extract relevant information. The existing classification methodologies for dissimilarities between objects collected in different occasions assume a unique common underlying classification structure. However, since the objects' clustering structure often changes along the occasions, the use of a single classification to reconstruct the taxonomic information frequently appears quite unrealistic. The methodology proposed here models the dissimilarities in a likelihood framework. The goal is to identify a (secondary) partition of the occasions in homogeneous classes and, simultaneously, a (primary) consensus partition of the objects within each of such classes. Furthermore, a class-specific dimensionality reduction operator is also included which allows to identify classes of occasions such that the within-class variability is minimized. The model is formalized as a finite mixture of multivariate normal distributions and solved by a numerical method based on ECM strategy.