variance

# variance - Why is the study of variability important...

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Why is the study of variability Why is the study of variability important? important? Allows us to distinguish between In some situations, want more/less variability scores on standardized tests time bombs medicine
Measures of Variability Measures of Variability range (max-min) interquartile range (Q3-Q1) deviations variance standard deviation ( 29 x x - ( 29 2 σ ( 29 Lower case Greek letter sigma

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Suppose that we have these data values: 24 34 26 30 37 16 28 21 35 29 Find the mean. Find the deviations. ( 29 x x - What is the sum of the deviations from the mean?
24 34 26 30 37 16 28 21 35 29 Square the deviations: ( 29 2 x x - Find the average of the squared deviations: ( 29 n x - = 2 2 μ σ

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The average of the deviations squared is called the variance . Population Sample 2 σ 2 s parameter statistic
Calculation of variance Calculation of variance of a sample of a sample ( 29 1 2 2 - - = n x x s n df

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variance - Why is the study of variability important...

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