The mean absolute deviation formula is Σ|x - μ| / N. The symbol Σ is used to denote the sum of a series of numbers, while μ represents the mean, x represents each value and N represents the total number of values. The formula takes the absolute value of the difference between a value and the mean and divides it by the number of values.
The mean absolute value of a data set, sometimes abbreviated as MAD, represents the mean of the data's absolute deviations about the data's mean. In other words, the mean absolute deviation represents the absolute value of the average distance from the data set's mean. The mean of a data set is the average of all of its values.