This document defines and describes several common measures used to describe data, including the mode, median, mean, range, interquartile range, and degrees of freedom. The mode is the most frequent value, the median divides the data in half, and the mean is the average. The range is the difference between the maximum and minimum values, while the interquartile range describes the spread between the first and third quartiles. Degrees of freedom refers to the number of independent observations in a data set.