Statistics Function -- Histogram Tab


The Statistics function enables you to describe the distribution of a data set.  When you select the Statistics (Statistics function button) toolbar button in the Data Table Window, the Statistics window appears.  This window begins on the Data & Analyses Selection tab.  After you select the data columns and specify that a Histogram analysis should be performed on the first tab, then click on the Histogram tab:  

Sample screen shot of Histogram Statistics tab

Type a name for the analysis that will appear as a table heading in the Data Table Window in the Tab Name field.

The Type group box contains the three available choices for the histogram values via the following radio buttons:

For reference only, the Data Range group box presents the minimum and maximum values of the actual data set.

The Binning group box contains three areas:

The binning specifications determine how the break points are set:

  1. If you select the Equally Spaced radio button as the Bin Type, specify values in the Lower bound, Upper bound, and the Number of bins (number of steps) fields in the binning specifications, then click the Recompute button to set these equally spaced break points.

  2. If you select the Custom radio button as the Bin Type, the break points are set manually using the toolbar above the Break Points table.

  3. If you select the Factor of 10 radio button as the Bin Type, specify values in the Lower bound and the Number of bins (number of steps) fields in the Binning group box, then the lower bound represents the first break point (note that the lower bound may not be set to 0), and subsequent break points are each 10 times greater than their predecessors.  The first break point is the upper limit for the first bin (the first bin extends from negative infinity to the first break point).

The Break Points table displays a row for each break point to be included.  Each row corresponds to one break point in the analysis.  Note that n bins will have n+1 break points (except for the Factor of 10 bin type).  The break points can only be selected and modified when the Custom radio button is selected in the binning specifications.   To insert a new row, click on one of the row numbers to select it and the display will change to white text on black.  Then click the mouse on the Insert Above (Insert Above icon) or Insert Below (Insert Below icon) toolbar buttons to create new rows; type the break point value directly into the box.  Click the Delete (Delete Row icon) toolbar button to remove the selected row(s).  To select multiple rows, hold down the Ctrl key (in MS Windows) while clicking the additional rows.  Click the Copy (Copy icon) toolbar button to save the value in the first selected row, and click the Paste (Paste icon) toolbar button to place the value into the selected row(s).  Click the Up (Up icon) and Down (Down icon) toolbar buttons to move the selected row higher and lower in the table (note that the break points must be in ascending order for the analysis to be performed).

Click OK button to close the Statistics window and add a new tab to the Data Table Window.  The new Sort Filter Table window appears similar to others:

Statistics-histogram table

Each row lists a bin and the value of the parameter (frequency, percentage, or probability) representing the amount of data in that bin.   

Click Cancel to close the Statistics window without making any changes.