Dynamic Graphics for Data Analysis

Dynamic graphical methods have two important properties: direct manipulation of graphical elements on a computer graphics screen and virtually instantaneous change of the elements. The data analyst takes an action through manual manipulation of an input device and something happens in real time on the screen. These computing capabilities provide a new medium for the invention of graphical methods for data analysis. A collection of such methods--identification, deletion, linking, brushing, scaling, rotation, and dynamic parameter control--is reviewed. Those who develop dynamic methods must deal with a number of computer hardware and software issues, because for a dynamic method to work there must be a sufficiently fast flow of information along the channel that starts with the analyst's input and ends with the changed graph. Furthermore, for a dynamic method to be useful, the visual and manual tasks must be easy to perform. Several computing issues dealing with speed and ease of use--system bandwidth, input and output devices, low-level algorithms, device independent graphics, and data analysis environments--are reviewed.