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## Range, variance, standard deviation

Levels are CK-12's student achievement levels.
Basic Students matched to this level have a partial mastery of prerequisite knowledge and skills fundamental for proficient work.
At Grade (Proficient) Students matched to this level have demonstrated competency over challenging subject matter, including subject matter knowledge, application of such knowledge to real-world situations, and analytical skills appropriate to subject matter.
Advanced Students matched to this level are ready for material that requires superior performance and mastery.

## Measures of Spread and Dispersion

This Concept introduces students to the some of the measures of spread commonly used, such as range, standard deviation and variance.

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• Video

## Summarizing Distributions: Measures of Variability

Discusses variability and statistical measures that can evaluate the spread of a distribution.

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## Statistics Worksheets

A webpage of basic statistics calculations and worksheets to practice with.

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## A Note on Standard Deviation

An experiment and explanation are offered as to why n-1 rather than n is used to calculate standard deviation.

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The answers to questions about standard deviation. Answers two questions: why a standard deviation takes the square root of the average of the sum of the squared differences between X and X mean, and why n vs n-1 is used in calculations.

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