nd IQR are the first quartile, third quartile, and
inter-quartile range, MC is the 'medcouple', a robust concept and
estimator of skewness, and a and b are appropriate constants (-4
and 3).  The medcouple is defined as a scaled median difference of
the left and right half of distribution, and hence not based on the
third moment as the classical skewness.</p>
<p>When the data are symmetric, the measure reduces to the
standard outlier rule also used in Tukey Boxplots (consistent with
the <code>boxplot</code> 