Given a statistical distribution with measured mean, mode, and standard deviation σ, the Pearson mode skewness is (mean - mode)/σ. The function was incorrectly implemented (with a spurious multiplicative factor of 3) in versions of the Wolfram Language prior to 6 as PearsonSkewness1[data] after loading the package StatisticsˋDescriptiveStatisticsˋ.

Bowley skewness | mean | mode | Pearson's skewness coefficients | skewness