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Semi-interquartile range

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Semi-interquartile range  (SEMI-INTERQUARTILE range)

The dispersion1, scatter1, variation1 (150-3) or variability1 of a set of observations depends on the differences2 or deviations2 (150-3) between its elements, Here the most common measures of dispersion3 only are mentioned. The range4 is the difference between the largest and the smallest value of a set of elements. The interquartile range5 is the difference between the first and third quartiles (cf. paragraph 142) and contains half the observations of the set. The semi-interquartile range6, also called the quartile deviation6, which is half the interquartile range, is often taken as a measure of dispersion. The mean deviation7 or average deviation7 is the arithmetic mean (140-2) of the positive values of the deviations of individual items from the average, the variance8 is the arithmetic mean of the squares of these deviations and the standard deviation9 is the square root of the variance.

  • 9. The common notation for the standard deviation is σ,