OLAP Visualization Operator for Complex Data Sabine Loudcher and Omar Boussaid ERIC laboratory, University of Lyon (University Lyon 2) 5 avenue Pierre Mendes-France, 69676 Bron Cedex, France Tel.: +33-4-78772320, Fax: +33-4-78772375 (omar.boussaid, sabine.loudcher)@univ-lyon2.fr Abstract. Data warehouses and Online Analysis Processing (OLAP) have acknowledged and efficient solutions for helping in the decision- making process. Through OLAP operators, online analysis enables the decision-maker to navigate and view data represented in a multi-dimensional manner. But when the data or objects to be analyzed are complex, it is necessary to redefine and enhance the abilities of the OLAP. In this paper, we suggest combining OLAP and data mining in order to create a new visualization operator for complex data or objects. This opera- tor uses the correspondence analysis method and we call it VOCoDa (Visualization Operator for Complex Data). Keywords : OLAP, Data Mining, Complex Data, Visualization 1 Introduction Data warehouses and Online Analysis Processing (OLAP) have recognized and effective solutions for helping in the decision-making process. Online analysis, thanks to operators, makes it possible to display data in a multi-dimensional manner. This technology is well-suited when data are simple and when the facts are analyzed with numeric measures and qualitative descriptors in dimensions. However, the advent of complex data has questioned this process of data ware- housing and online analysis. Complex data often contain a document, an image, a video, ..., and each of these elements can be described and observed by a set of low-level descriptors or by semantic descriptors. This set of elements can be seen not only as com- plex data but also as a complex object. A complex object is a heterogeneous set of data, which, when combined, form a semantic unit. For instance, a patient’s medical record may be composed by heterogeneous elements ( medical test re- sults, X-rays, ultrasounds, medical past history, letter from the current doctor, ...) and is a semantic unit. It is a complex object. As said above, warehousing and online analytical processes must be modified in the case of complex objects. In this paper, we focus on the visualization of complex objects. The problem of storing and modeling complex objects is dis- cussed in other articles. The purpose of online analysis is to (1) aggregate many data to summarize the information they contain; (2) display the information