interquartile range
(noun)Definition of interquartile range
The difference between the first and third quartiles; a robust measure of sample dispersion.
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Examples of interquartile range in the following topics:

Interquartile Range
 The interquartile range (IQR) is a measure of statistical dispersion, or variability, based on dividing a data set into quartiles.
 The interquartile range is equal to the difference between the upper and lower quartiles: IQR = Q3 − Q1 It is a trimmed estimator, defined as the 25% trimmed midrange, and is the most significant basic robust measure of scale.
 This is the Interquartile range, or IQR.
 Uses Unlike (total) range, the interquartile range has a breakdown point of 25%.
 In other words, since this process excludes outliers, the interquartile range is a more accurate representation of the "spread" of the data than range.
 The interquartile range (IQR) is a measure of statistical dispersion, or variability, based on dividing a data set into quartiles.

The Density Scale
 In addition to the points themselves, box plots allow one to visually estimate the interquartile range.
 A range of data clustering techniques are used as approaches to density estimation, with the most basic form being a rescaled histogram.
 To see this, we compare the construction of histogram and kernel density estimators using these 6 data points: x1 = −2.1, x2 = −1.3, x3 = −0.4, x4 = 1.9, x5 = 5.1, x6 = 6.2 For the histogram, first the horizontal axis is divided into subintervals, or bins, which cover the range of the data.

Graphs of Qualitative Data
 Median, measures of shape, measures of spread such as the range and interquartile range, require an ordered data set with a logical lowend value and highend value.

Outliers
 Another method often used is based on the interquartile range (IQR).

Outliers
 Other methods flag observations based on measures such as the interquartile range (IQR).