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In this module, you can study the basic statistical measures of dispersion: range, variance and standard deviation.

The video above is a good explanation from Khan Academy about statistical measures of dispersion: range, variance and standard deviation.

Variation and standard deviation both show how spread out the data set is.

A data set of any size can have a large or a small standard deviation.

- Study rangeThis page from mathgoodies.com explains how to find the range of a data set. After you read through the examples, you can try a few problems of your own.
- Study variance and standard deviationMathsisfun.com does a good job of explaining how to find variance and standard deviation. At the end of this page, you will find a quiz to test your knowledge. For a more advanced discussion, see www.onlinemathlearning.com/variance.html.
- Quiz yourself on standard deviationThis five-question quiz from usablestats.com checks your understanding of the concept of standard deviation.
- Quiz yourself on standard deviation by building your own quizMake a list of numbers (a data set) and use this online calculator to find the standard deviation of the set. Compare the calculator's answer to your own worked-out answer to see if you have it right.

Use these search terms to find your own resources:

*measures of dispersion
range, variance and standard deviation*