Graphics Exploratory data analysis and data mining often begin with graphical analysis of the data before techniques, like regression analysis, are even applied. Here S-PLUS shines in its abundance. For example, after selecting two data columns, pushing the 2D-graph button summons up a menu of almost fifty graph types. More importantly, graphs with multiple x or y axes are very easily implemented. When the graph is completed, a wizard can be invoked to transfer the graph into Microsoft Powerpoint.
Trellis graphics are an important graphics tool that can provide analytical insight.
The single plot of X versus Y becomes multiple plots, each one valid for a selectable range of the Z variable. Financial engineers could, for example, use this feature to see how the history of price changes may depend conditionally on a tertiary variable Z. Figure 1 shows an application of Trellis graphics in technical analysis. In the futures market, changes in open interest and volume are believed to influence price changes. Trellis graphics plot the history in price changes for cases of negative and positive changes in open interest and in volume. Contrary to popular belief, these plots demonstrate no strong pattern of influence exists for this particular market.