11.2.2 Absolute deviation
Compute the absolute deviation from the mean of data The absolute
deviation from the mean is defined as
are the elements of the dataset data. The absolute
deviation from the mean provides a more robust measure of the width of a
distribution than the variance. This function computes the mean of
data via a call to mean.
Compute the absolute deviation of the dataset data relative to the
given value of mean
This function is useful if you have already computed the mean of data
(and want to avoid recomputing it), or wish to calculate the absolute
deviation relative to another value (such as zero, or the median).