In previous grades, you used different statistical measures to describe the central tendency and variability, or spread, of a data set.

**Central Tendency**

The central tendency of a data set is used to describe the “typical” value in a data set. Two common measures of central tendency are mean and median.

**Variability**

The variability, or spread, of a data set is used to describe how far apart the numbers are in a data set. Two commonly used measures of variability are range and interquartile range.

In this lesson, you will investigate an additional measure of variability, the mean absolute deviation. The mean absolute deviation of a data set tells you the typical distance between each number in the data set and the mean of the data set.