18+ Interquartile Range Formula Pics. To find the interquartile range (iqr), first find the median (middle value) of the lower and upper half of the data. For calculating the interquartile range, firstly, we need to calculate the quartiles.

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Now comes the turn of interquartile range. It is calculated as the difference between the first quartile* (q1) and the note that we could also have found the interquartile range of the dataset in the previous example by using one formula The quartiles are the three values that split the sorted data set into four equal parts.

The interquartile range is found by subtracting the q1 value from the q3 value:

The interquartile range, often denoted iqr, is a way to measure the spread of the middle 50% of a dataset. The interquartile range is a much better measure of variation than the regular range (maximum value minus minimum value). The quartiles are the three values that split the sorted data set into four equal parts. The interquartile range is an especially useful measure of variability for skewed distributions.