The Bowley skewness, also known as quartile skewness coefficient, is defied by ((Q_3 - Q_2) - (Q_2 - Q_1))/(Q_3 - Q_1) = (Q_1 - 2Q_2 + Q_3)/(Q_3 - Q_1), where the Qs denote the interquartile ranges. It is implemented in the Wolfram Language as QuartileSkewness[data].