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Unformatted text preview: change from sample to sample: Sample statistics are random variables ! Measures of dispersion for sample data Preliminary note In physics, the moment of inertia is calculated by using the center of gravity of the object as point of reference. In statistics, the most used measure of dispersion for sample data (i.e., the sample variance) is evaluated by using the sample mean as point of reference. Note By definition, (1) The sample variance is non-negative. (2) The sample standard deviation is expressed in the same unit as the sample mean and the random variable of interest. (3) The coefficient of variation allows one to compare the dispersion of ‘apples and oranges’ = samples of data collected for two random variables expressed in different units or samples of data with very different means....
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- Spring '08
- Standard Deviation