2D Histograms - Quick Tab

Click the Variables button to display a standard variable selection dialog box, in which you select the variable(s) to be plotted. When you select more than one variable for a Regular histogram, a sequence of graphs will be produced (one for each of the variables). Note that you can select up to 300 variables at a time.

Select the type of 2D histogram to be plotted from the Graph type list. Click the following links to obtain a brief description of the graph types. These graph types, as well as the Double-Y type, are also available on the Advanced tab.

Regular

Multiple

Select this check box to superimpose a normal fit over the histogram. For more information on the normal fit (and the other fit types available on the Advanced tab), see Fitted Functions for Histograms and Graphs in Statistica.

Use the options in the Intervals group box to specify a method of categorization of the values in the histogram for the selected variable(s). Note that four categories are available on the Quick tab: Integer mode, Unique values, Categories, and Codes. More categorization methods are available on the Advanced tab.

Integer mode. Use this option to automatically identify the most informative method of categorization. If the Auto check box is selected (default), the program will automatically categorize ("bin") the values of the selected variable(s) into "neat" intervals, yielding the simplest interval boundaries and step sizes possible, to create the most easily interpretable graphs. If you clear the Auto check box, the program will assume that the values in the respective variable(s) are all integer values, and truncate (not round) all non-integer values to integers before binning.

Auto check box selected. The Auto check box is used to automatically identify the most informative method of categorization. The program will identify from the data the appropriate boundaries and step sizes for the bins that will yield the most easily interpretable graph. This method of categorization is also referred to as neat scaling: "Neat" categories in this context means that Statistica chooses a step size with the only significant digit being either 1, 2, or 5 (e.g., possible step sizes could be .1, .05, 50, 200, etc.). However, if you want to force single integer categories (e.g., if you want to produce a histogram for 100 different integer values), clear the Auto check box to create categorizations (binning) as described in the next paragraph.

Auto check box not selected. When this check box is cleared, Statistica truncates (not rounds) each encountered value of the selected variable to an integer value, and creates one category for each integer. For example, all values 2.1, 2.4, 2.5, 2.8, ... would be truncated to the integer value 2, and counted in that (integer) category. If the nature of the data is continuous (with fractional values), in order to obtain a detailed picture of the distribution of the respective variables, accept the default Auto option (leave the check box selected), which causes values to be binned (assigned to categories) as described in the previous paragraph.

When you select this method, Statistica will create one category (or graph in the case of categorized graphs) for each unique value. The unique values can be either floating point or integral, and Statistica can handle up to 255 unique values.

The following options dictate how the categories are organized in the graph:

Unsorted. Select the Unsorted option button to plot the categories in the same sequence as they occur in the data set.

Asc. Select the Asc option button to plot the categories in ascending order.

Desc. Select the Desc option button to plot the categories in descending order.

Select this option button and enter the desired number of categories in the adjacent box. The program then divides the entire range of values of the selected variable (from minimum to maximum) into the requested number of equal length intervals. Cases with values of the selected variable that belong to each interval will compose one category.

Select this option button if the selected variable contains codes from which you want to specify the categories. After you select this option, click the none button and enter the desired codes in the Category Codes dialog box (note that if you have not yet selected variables, a variable selection dialog box will first be displayed).