interquartile range

(noun)

The difference between the first and third quartiles; a robust measure of sample dispersion.

Related Terms

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:
    • This is the Interquartile range, or IQR.
    • 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.

  • Measures of Variability

    • There are four frequently used measures of variability: range, interquartile range, variance, and standard deviation.
    • The interquartile range (IQR) is the range of the middle 50% of the scores in a distribution.
    • The interquartile range is therefore 2.
    • A related measure of variability is called the semi-interquartile range.
    • The semi-interquartile range is defined simply as the interquartile range divided by 2.

  • Exercises

    • : mean, median, mode, trimean, geometric mean, range, interquartile range, variance, standard deviation
    • (AM#8) What is the range of the Anger-In scores?
    • What is the interquartile range?
    • (SL#2) Find the mean, median, standard deviation, and interquartile range for the leniency scores of each of the four groups.
    • (AT#7) What are the standard deviation and the interquartile range of the d0 condition?

  • Practice 1: Center of the Data

    • Exercise 2.11.13: Interquartile range (IQR) = _____ - _____ = _____

  • Box plots, quartiles, and the median

    • The total length of the box, shown vertically in Figure 1.25, is called the interquartile range (IQR, for short).

  • 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.
    • For the histogram, first the horizontal axis is divided into sub-intervals, or bins, which cover the range of the data.

  • Lab: Continuous Distribution

    • IQR means interquartile range. )

  • Measures of the Location of the Data

    • The interquartile range is a number that indicates the spread of the middle half or the middle 50% 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 low-end value and high-end value.

  • Outliers

    • Other methods flag observations based on measures such as the interquartile range (IQR).
    • Rhode Island, Texas, and Alaska are outside the normal data range, and therefore are considered outliers in this case.