Variance
Variance
the standard deviation squared, [latex]\sigma^{2}[/latex] or [latex]s^{2}[/latex]
Variance of a population: [latex]\sigma^{2}=\dfrac{\sum\left(x-\mu\right)^{2}}{n}[/latex]
Variance of a sample: [latex]s^{2}=\dfrac{\sum\left(x-\bar{x}\right)^{2}}{n-1}[/latex]
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Important: The statistical technology tool does not calculate variance, so you will need to use the tool to calculate the standard deviation and then square it by hand in order to get the variance.
Range
Range
maximum value – minimum value
or
largest value – smallest value
When the range is larger, it indicates more variability in the data. However, range only utilizes two observations in the entire data set to measure variability, so it is not an ideal measure of spread when used alone. But when used in combination with other measures of variance, it can help us gain a clearer understanding of the spread of a distribution.
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