How Do I Calculate the Upper or Lower Quartile?

By Staff WriterLast Updated Mar 24, 2020 6:28:24 PM ET
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To find the first quartile of a set of numbers, find the median of the lowest half of the data set. This median is the first, or lowest, quartile in the data set. To find the third, or upper, quartile of a data set, instead find the median of the higher half of numbers in the set.