Mean -to-MAD ratio is the division of the Mean by the Mean Absolute Deviaion (MAD). For the set 1, mean / MAD is 10.3 / 1. 6 = 6.4375; and for the set 2, Mean / MAD is: 12.7 / 1.5 = 8.467. This is a measure of disperssion of a set of values. MAD is calculated as the sum of the absolute differences of the values and the mean.