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Unformatted text preview: r mal, is approximately nor mal for sufficiently large sample sizes. The definition of “sufficiently large” depends on the ext e Statistics Review Positively Skewed – The right tail is longer and most of the data is concentrated on the LEFT of the figure. Also referred to as “skewed to the right”. Negatively Skewed – The left tail is longer and the most of the data is concentrated on the R IG HT of the figure. Also referred to as “skewed to the left”. Population mean: μ = = i 1NxiN Sample mean: = = i 1nxin Population variance: σ 2 = = ( ) i 1N xi μ 2N Sample variance: s 2 = = () i 1N xi 2n 1 Population standard deviation: = σ σ2 (square root of the population variance) Sample standard deviation: s = s2 (square root of the sample variance) Empirical Rule – 68% of all observations fall within one standard deviation of the mean, 95% of all observations fall within two standard deviations of the mean, and 99.7% of all observations fall within three standard deviations of the mean. (689599.7)observations fall within three standard deviations of the mean....
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 Spring '08
 KOUZEHKANANI
 Standard Deviation, Variance, population variance, ly lar ge, i=1nxin Population variance

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