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A histogram is a frequency diagram and statistical tool that performs non-parametric density estimation.

To launch the histogram editor, select Visualize > Histogram from the menu. Alternatively, click the icon () in the sidebar and then add New.

Create a Histogram

The parameters for a histogram are defined on two tabs at the top of the page: Data and Properties.

On the Properties tab:

Select a Record set from the list.
Select from the Variable list and set an variable for X, and one for C (Condition), if required.

Find a Variable

Variables are listed alphabetically. To find a variable, enter a name in the Variable field.

On the Advanced tab:

Enter a chart Title.
Enter Font Size of the graphic, if required.
Select Show statistics to display standard deviations and average values. A bell curve displays corresponding to the theoretical normal (Gaussian) distribution using the mean (average) and standard deviation of the selected record set.
Select Legend position, the Default position is on the left-corner of the graph. You can also have the option of have no legend (None).
Select Conditional class count for the condition or number of discretized groups for a conditional variable added as color coding to Histograms. For more information, see Conditional class count.
Select a Plot Type for the drop down list:
1. Histogram is a graphical representation of a numerical data distribution. For a numerical variable, the data is divided into consecutive and non-overlapping adjacent intervals, often of equal sizes. The height of each bar is proportional to the frequency – number of cases per interval. For symbolic variables, the intervals represent the classes (categories) of that variable.
2. Pareto is a bar graph for symbolic variables only, where the symbols are represented in descending order. The lengths of the bars represent the frequency of occurrence of the set of categories of a symbolic variable. The purpose of this chart is to highlight the most important among a large set of categories.
3. Cumulative plot is a curve that shows the cumulative frequency distribution.
Select the check box for Relative frequencies to display the Y axis as a percentage (number of records in a bar / total number of records in the set). See glossary Relative Frequencies.
Define zoom area using X axis, Y axis and Y' axis. Select a date in the calendar in X axis. Enter the values of Y and Y'axis.
Click Save to load the data.

Change number buckets

To change the number of buckets for the Condition, use Cond. Class Count.

Choose color for condition variable

If you want to define a color to a symbolic variable used as a Condition, use the Preferences task.

Control the View

Use the control menu below the chart to modify the zoom, apply rulers to create new record sets. For more information, see Control Menu.

Copy/Save Histogram

To copy or save the curve click on the curve with the right click and select Copy image or Save image as.

Example Visualization

The following example illustrates the seasonal daytime weekly averages of electrical consumption.

Histograms