1. Measures of Variability
Standard Deviation and Variance


The two histograms below show datasets with the same measures of central tendency: the means, medians, and modes are equal to 0.

The mean, the median, and the mode each tell us about the general center of the dataset. But these two histograms are not similar. The first one has all the information near the center, whereas observations from the second one are scattered away from the center. Therefore, the difference lies in the variability or dispersion of the data.

In this section we will now discuss common measures of variability.