Interquartile range (IQR) or midspread or middle fifty is the difference between the third and the first quartiles in statistical dispersion. It is nothing but 1st quartile subtracted from the 3rd quartile. It can be clearly figured out in box plot on the data and it helps in measuring the variability on the basis of division of data set in the quartiles. Make use of this free InterQuartile Range (IQR) calculator to find the interquartile range from the set of observed numerical data.
Let us consider the following numbers: 1, 4, 5, 6, 6, 7, 11, 12, 15, 17
Q1 is the middle value in the first half of the data set i.e 5
Q3 is the middle value in the second half of the data set i.e 12
Sum of all the numbers divided by total number of values
Median = 1 + 4 + 5 + 6 + 6 + 7 + 11 + 12 + 15 + 17 / 10
The interquartile range is Q3 minus Q1, so IQR = 12 - 5