Introduction to the special issue on interactive graphical data analysis: What is interaction?

In this introduction to the special issue of Computational Statistics on interactive graphical data analysis, we first briefly introduce the papers. They cover a lot of ground, from the updating of older statistical environments to the assessment of some of the newest, and there are several interesting examples of interactive graphics applied to data analysis problems. Afterwards, we describe a questionnaire we circulated in an effort to learn about the application of interactive graphical methods to data analysis in practice. We received too few responses to find the answers to our questions, but we did observe a few interesting things. In particular, we realized that conflicting uses of the term ``interactive{''} are currently in use, muddying our discussions of software design and data analysis practice. We'll discuss our observations in terms of the papers in this issue. We invite you to visit http://comst.wiwi.hu-berlin.de/issue0199.html for links to color versions of many of the graphics in the papers in this issue, as well as additional graphics provided by the authors.