Ch5_Variability

# Ch5_Variability - Chapter 5 Measures of Variability...

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Chapter 5 Measures of Variability

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Variability and Range Variability : How much scores vary from each other. Range : The spread, or dispersion, from the highest to the lowest score. Range = X highest - X lowest
Quartile Ranges Interquartile range : used with ordinal data X 75 - X 25 which provides the range of scores of 50% of the subjects around the median. Semi-Interquartile range : (X 75 - X 25 ) / 2 provides the range of the scores of 50% of the subjects above and below the median

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Variance Variance is the most used statistic to measure the variability of a variable. Variance can be obtained by subtracting the mean of a distribution from each score in the distribution, squaring each difference, summing the differences, and then dividing the sum by the number of scores in the distribution.
Sample Variance and Population variance Population 2 2 2 D Sample 2 2 N ) X ( Variance Population N X N ) X X ( S Variance Sample - = = = - = = μ σ

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## Ch5_Variability - Chapter 5 Measures of Variability...

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