Mapping Nominal Values to Numbers for Effective Visualization

Data sets with a large number of nominal variables, some with high cardinality, are becoming increasingly common and need to be explored. Unfortunately, most existing visual exploration displays are designed to handle numeric variables only. When importing data sets with nominal values into such visualization tools, most solutions to date are rather simplistic. Often, techniques that map nominal values to numbers do not assign order or spacing among the values in a manner that conveys semantic relationships. Moreover, displays designed for nominal variables usually cannot handle high cardinality variables well. This paper addresses the problem of how to display nominal variables in general-purpose visual exploration tools designed for numeric variables. Specifically, we investigate (1) how to assign order and spacing among the nominal values, and (2) how to reduce the number of distinct values to display. We propose that nominal variables be preprocessed using a Distance-Quantificat...

• Type: Conference
• Year: 2003
• Where: INFOVIS
• Authors: Geraldine E. Rosario, Elke A. Rundensteiner, David C. Brown, Matthew O. Ward
• Keywords: INFOVIS 2003, Nominal Values, Nominal Variables, Visual Exploration