ISDS 2000 Lecture : Test 1-Lecture 4
15 Mar 2019
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Document Summary
9/8/2014 7:36:00 pm: an average of the absolute difference of each observation from the mean. Variance and standard deviation: for a given sample(standard deviation for sample) 2 s: for a given population(standard deviation for population) 2: no need for absolute value because when you square it, it will be positive. Coefficient of variation(cv: adjusts for differences in the magnitudes the of means, unitless, allowing easy comparisons of mean-adjusted dispersion across different data sets. Measures of shape: shape, the manner in which data are distributed, symmetrical distribution, one half of the data is the mirror image of the other half, skewed distribution, right-skewed, left-skewed. The empirical rule: approximately 68% of all observations fall in the interval, approximately 95% of all observations fall in the interval s , almost all observation fall in the interval. 2x x s : used to remove outliers; any data outside this range is deleted because it is skewing results.
