Click on the horizontal axis to select data points in the interval \( [0, w] \); the points are shown as red dots on the horizontal axis and are recorded in the fist table. The graph shows the error function, which can be selected as either root 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. The statistics table records the mean and standard deviation, and the minimum value, first quartile, median, third quartile, and maximum value. The width \( w \)of the interval can be varied with the input control.