Clustering and Classification Bsed on the L1 Data Depth

• Activity Number: 35
• Type: Invited
• Date/Time: Sunday, August 8, 2004 : 4:00 PM to 5:50 PM
• Sponsor: Section on Physical and Engineering Sciences
• Author(s): Rebecka J. Jornsten*+
• Companies: Rutgers University
• Keywords: clustering ; classification ; data depth ; validation ; microarray ; gene expression

Abstract

Clustering and classification are important tasks for the analysis of microarray gene expression data. Classification of tissue samples can be a valuable diagnostic tool for diseases such as cancer. Clustering samples or experiments may lead to the discovery of subclasses of diseases. Clustering can also help identify groups of genes that respond similarly to a set of experimental conditions. In addition to these two tasks it is useful to have validation tools for clustering and classification. Here we focus on the identification of outliers--units that may have been misallocated, or mislabeled, or are not representative of the classes or clusters. We present two new methods: Ddclust and Ddclass, for clustering and classification. These robust nonparametric methods are based on the intuitively simple concept of data depth. We apply the methods to several gene expression and simulated datasets. We also discuss a convenient visualization and validation tool--the Relative Data Depth (ReD) plot.