# Descriptive Statistics - Prob. & Scatterplots tab

Select the Prob. & Scatterplots tab of the Descriptive Statistics dialog box to access options to create a variety of scatterplots and probability plots. Scatterplots are used to visualize a relation between two or more variables. Probability plots are used to evaluate the normality of the distribution of a variable, that is, whether and to what extent the distribution of the variable follows the normal distribution.

2D scatterplot / with names. Click either button to produce a cascade of scatterplots for selected pairs of variables. A variable selection dialog box is displayed, in which you select the variable(s) for the x- and y-axes; one plot is produced per variable pair. When you click the 2D scatterplot button, the plot shows the regression line and the standard error of the predicted values (as error lines) in the scatterplot. When you click the with names button, the scatterplot does not contain those lines, but identifies the points in the scatterplot with the case numbers or names (if case names are specified in the respective data file).

3D scatterplot / with names. Click either button to produce a 3D scatterplot for a selected triplet of variables. A variable selection dialog box is displayed, in which you select the variable for the x-, y-, and z-axes. When you click the with names button, the points in the scatterplot are identified by the case numbers or names (if case names are specified in the respective data file).

Categorized scatterplot. Click this button to produce a cascade of categorized scatterplots for selected pairs of variables, one plot per pair. You are first prompted via a variable selection dialog box to select two lists of variables (from among those originally selected via the Variables button). Scatterplots are produced for each variable in the first list with each variable in the second list. Next (via another variable selection dialog box) you are prompted to select up to two categorical variables. Then the Select Codes for the Grouping Variables dialog box is displayed, in which you specify the specific groups of each of your categorical variables for which you want graphs to be produced. Finally, Statistica produces a cascade of scatterplots broken down (categorized) by the specified groups in the categorical variables. Note that more complex breakdown analyses and graphs are available via the Breakdown & one-way ANOVA analysis.

Surface plot. Click this button to produce a surface plot for a selected triplet of variables, and fit a quadratic surface to the data. A variable selection dialog box is displayed, in which you select the variables for the plot.

Scatterplot matrix. Click this button to produce a scatterplot matrix for selected variables. A variable selection dialog box is displayed, in which you select the variables for the plot.

Normal probability plot. Click this button to produce a cascade of normal probability plots for the selected variables, one plot per selected variable. For more information on how the standard normal probability plot is constructed, see Normal Probability plots.

Half-normal probability plot. Click this button to produce a cascade of half-normal probability plots for the selected variables, one plot per selected variable. For more information on how the half-normal probability plot is constructed, see Half-Normal Probability Plots.

Detrended normal probability plot. Click this button to produce a cascade of detrended normal probability plots for the selected variables, one plot per selected variable. For more information on how the detrended normal probability plot is constructed, see Detrended Normal Probability Plots.