Division of the total cases or observations in a study into four groups of equal size.
n. one of four equal parts into which a rank-ordered data set is divided. The interquartile range is the difference between the upper quartile and the lower quartile and gives a clear indication of the central 50% of the values.
The central portion of a distribution, calculated as the difference between the third quartile and the first quartile; this range includes about one half of the observations in the set, leaving one quarter of the observations on each side.... interquartile range
(Latin) The fourth-born child Quartillah, Quartila, Quartylla, Quartyla, Quartille, Quartylle, Quartile, Quartyle... quartilla
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