The X-Y scatter plot is one of the most powerful tools for
exploratory data analysis. GRAPHID includes a host of features to enhance the
basic scatter plot. These features are:
- Multi-window option for simultaneous plotting of several scatter
plots. This option allows the visualization of relationships between
several variables at a time, for example, the predictors of a regression
model to look for multicollinearity.
- Identification of cases in a scatter plot. This option is
particularly useful to identify the outlier cases.
- Regression lines:
Three different types of regression lines can be displayed on each scatter
These are nonparametric regression lines, which are constructed through
smoothing with order statistics (k- nearest neighbor smoothing). The
number of neighbors is to be decided by the researcher.
- Histograms of variables can be plotted on the diagonal windows
of the multi-window scatter plot, to visualize the distributions of
- Density plots are essentially smooth versions of histograms.
They provide smooth estimates of probability density curve. Order statistics can be used for constructing
nonparametric density estimates. Let i be the number of points in a
gate of width r corresponding to the point X (i) and
let I (i) =X (i+ r) – X (
i – r),. The density of the point X (i) = I (i)/2