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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: = = i 1NxiN Sample mean: = = i 1nxin Population variance: 2 = = ( ) i 1N xi 2N Sample variance: s 2 = = () i 1N xi 2n 1 Population standard deviation: = 2 (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

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