Click on the horizontal axis in the first graph to select points for a frequency distribution. The frequency distribution is given in the data table, and the corresponding histogram is shown in the first graph. The class width (and hence the number of classes) can be varied with the scroll bar. The vertical axis can be selected as either frequency or relative frequency from the list box.
The second graph shows the error function, which can be selected as either mean square error or mean absolute error. In the first case, the minimum occurs at the mean and the minimum value is the variance. In the second case, the minimum occurs throughout the median interval and the minimum value is the mean absolute deviation from the median.