SPAN 101 Chapter Notes - Chapter 5: Squared Deviations From The Mean, Interquartile Range, Standard Deviation
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If the shape is skewed: report the median and iqr, mean + standard deviation (mean and median differ) If the shape is unimodal and symmetric: mean and standard devation, possibly the median and iqr, unimodal: iqr is usually a bit larger than the standard deviation. Boxplots: centre: a box that shows the middle half of the data, height of the box: iqr, upper fence = q3 + 1. 5 iqr, lower fence = q1 1. 5 iqr, whiskers: skewness. Gm: (cid:523)(cid:883)+r(cid:883)(cid:524) x (cid:523)(cid:883)+r(cid:884)(cid:524) x x(cid:523)(cid:883)+rn(cid:524) - 1 (m: n/(cid:523)(cid:883)/y(cid:883)+(cid:883)/y(cid:884)+ (cid:883)/yn(cid:524) Average: = total / n = ey/n. Median: resistant to unusual observations or shape of the distribution. Geometric: used for rates where each measurement depends on the previous one. Harmonic: rates that are not dependent on each other. Interquartile range (iqr): summarizes the spread by focusing on the middle half of the data. Standard deviation: measures of spread to have the same units as the data.
