stats (version 3.3)

IQR: The Interquartile Range

Description

computes interquartile range of the x values.

Usage

IQR(x, na.rm = FALSE, type = 7)

Arguments

x

a numeric vector.

na.rm

logical. Should missing values be removed?

type

an integer selecting one of the many quantile algorithms, see quantile.

Details

Note that this function computes the quartiles using the quantile function rather than following Tukey's recommendations, i.e., IQR(x) = quantile(x, 3/4) - quantile(x, 1/4).

For normally $N(m,1)$ distributed $X$, the expected value of IQR(X) is 2*qnorm(3/4) = 1.3490, i.e., for a normal-consistent estimate of the standard deviation, use IQR(x) / 1.349.

References

Tukey, J. W. (1977). Exploratory Data Analysis. Reading: Addison-Wesley.

See Also

fivenum, mad which is more robust, range, quantile.

Examples

IQR(rivers)