What is "medcouple"

The medcouple is a robust statistic that measures the skewness of a univariate distribution. Its robustness makes it suitable for identifying outliers in adjusted boxplots. Ordinary boxplots do not fare well with skew distributions, since they label the longer unsymmetrical tails as outliers. Using the medcouple, the whiskers of a boxplot can be adjusted for skew distributions and thus have a more accurate identification of outliers for non-symmetrical distributions.

As a kind of order statistic, the medcouple belongs to the class of incomplete generalised L-statistics. Like the ordinary median or mean, the medcouple is a nonparametric statistic, thus it can be computed for any distribution.