<Table> <Tr> <Td> </Td> <Td> This article needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (May 2012) (Learn how and when to remove this template message) </Td> </Tr> </Table> <Tr> <Td> </Td> <Td> This article needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (May 2012) (Learn how and when to remove this template message) </Td> </Tr> <P> In descriptive statistics, the interquartile range (IQR), also called the midspread or middle 50%, or technically H - spread, is a measure of statistical dispersion, being equal to the difference between 75th and 25th percentiles, or between upper and lower quartiles, IQR = Q − Q. In other words, the IQR is the first quartile subtracted from the third quartile; these quartiles can be clearly seen on a box plot on the data . It is a trimmed estimator, defined as the 25% trimmed range, and is the most significant basic robust measure of scale . </P> <P> The IQR is a measure of variability, based on dividing a data set into quartiles . Quartiles divide a rank - ordered data set into four equal parts . The values that separate parts are called the first, second, and third quartiles; and they are denoted by Q1, Q2, and Q3, respectively . </P>

What is the meaning of iqr in math
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