The mean absolute deviation (MAD) is a measure of the spread of a data set that measures how much the data elements differ from the mean. The mean absolute deviation is the average distance between each data value and the mean. Calculating the MAD involves determining the absolute difference between every data point and the mean, followed by averaging these absolute differences. The applet below calculates the mean absolute deviation for the data set on the number line. Move the points around to change the data. A large MAD value indicates that data points deviate considerably from the mean — that is, there is significant variation within the data set. The mean absolute deviation is less sensitive to outliers compared to standard deviation and variance because it calculates the average of the absolute differences.