R: The Interquartile Range

IQR {base} | R Documentation

## The Interquartile Range

### Description

computes interquartile range of the `x` values.

### Usage

    IQR(x, na.rm = FALSE)

### Arguments

`x` | a numeric vector.
`na.rm` | logical. Should missing values be removed?

### 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

    data(rivers)
    IQR(rivers)

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