

   TThhee IInntteerrqquuaarrttiillee RRaannggee

        IQR(x, na.rm = FALSE)

   DDeessccrriippttiioonn::

        computes interquartile range of the `x' values.

   DDeettaaiillss::

        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'.

   RReeffeerreenncceess::

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

   SSeeee AAllssoo::

        `fivenum', `mad' which is more robust, `range', `quan-
        tile'.

   EExxaammpplleess::

        data(rivers)
        IQR(rivers)

