3.11 Variability
Variability refers to how much the numbers in a distribution differ from each other. The most common measures are presented in "Measures of Variability." The "variability demo" allows you to change the standard deviation of a distribution and view a graph of the changed distribution.
One of the more counter-intuitive facts in introductory statistics is that the formula for variance when computed in a population is biased when applied in a sample. The "Estimating Variance Simulation" shows concretely why this is the case.
Adapted from Online Statistics Education: A Multimedia Course of Study (onlinestatbook.com), Project Leader: David M. Lane, Rice University. Developed with NSF support. The original work is in the public domain; it is cited here at the authors' request. Changes were made: reformatted as an accessible XYZ web edition with native MathML. License: Public-Domain.