medcouple

wikipedia: "In statistics, the medcouple is a robust statistic that measures the
skewness of a univariate distribution[1]. It is defined as a scaled
median difference of the left and right half of a distribution. Its
robustness makes it suitable for identifying outliers in adjusted
boxplots[2][3]."

1 = G. Brys; M. Hubert; A. Struyf (November 2004). "A Robust Measure of
Skewness". Journal of Computational and Graphical Statistics. 13
(4): 996–1017.
2 = M. Hubert; E. Vandervieren (2008). "An adjusted boxplot for skewed
distributions". Computational Statistics and Data Analysis. 52 (12):
5186–5201. doi:10.1016/j.csda.2007.11.008.
3 = Pearson, Ron (February 6, 2011). "Boxplots and Beyond – Part II:
Asymmetry". exploringdata.blogspot.ca. Retrieved April 6, 2015.