Stats test notes - Stats test notes Interquartile Range=...

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Stats test notes: Interquartile Range= third quartile minus first quartile Sample variance-sum of squared standard deviations divided by n-1=(standard deviation) squared Coefficient of variation: ratio of standard deviation to the mean Population variance-divide by N instead Population standard deviation=square root of population variance Skewed to the right=data is more to the left=positive skewness value When the distribution is skewed right, the mean is usually greater than the median. When the distribution if skewed left, the median is usually grater than the mean. Chebyshev’s theorem-65 percent of data must be within 1.7 standard deviation of the mean Norman distribution-data clustered around the mean Empirical rule-65, 95, 99.7 percent of data are within 1,2,3 standard deviations of the mean respectively. Empirical rule may not hold for right skewed data Lower limit=Q1-1.5(IQR) Upper Limit=Q3+1.5(IQR) Sample covariance=multiply deviations from the mean and divide by N-1 Sample correlation coefficient=ratio of sample covariance to the product of the standard deviations of both variables. Weighted mean=multiply value by number of occurrences, add them all up, divide by total number of occurrences Sample mean for grouped data=sum of class midpoints times frequencies divided by total frequencies.
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This note was uploaded on 02/09/2010 for the course ECON ECON111 taught by Professor Smith during the Spring '09 term at Punjab Engineering College.

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Stats test notes - Stats test notes Interquartile Range=...

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