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Measures of Dispersion

Measures of Dispersion

Author: Sara Gorsuch
Description:

Define and explain these new terms:
+Range
+Deviation from the mean
+Mean absolute deviation
+Variance

Bringing you through the ideas behind range, deviation from the mean, mean absolute deviation, variance and showing you how it works, showing examples of how it all is put together into one idea.

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Tutorial

Range:  It’s the difference between the highest (largest) value (H) - the lowest (smallest) value (L) pieces of data.

so    range = H(highest value) -L(lowest value)

-----> some people also look at this as range= max(x) - min(x)

 Variance:  Is a sample measure of the spread of data about the mean.

 Mean absolute deviation: tells us the average distance that a piece of data is from the mean.

 

What are the formula for these?

  To find the formulas for these parts of standard deviation look through this great pdf, find the glossary section on the far right hand side and look

under measures of dispersion.   

http://www.statistics.com/resources/statsymbols.pdf

 

  

Measures of Dispersion

Source: Elementary Statistics : Sixth Edition: Robert Johnson.

Example of Finding the Sample of Variance.

This video describes what the variance is and shows us examples of how to calculate it. (It does briefly go into standard deviation)

Source: Khan Academy