https://en.wikipedia.org/wiki/Skewness
http://brownmath.com/stat/shape.htm
This method tends to match Excel's SKEW.P function.
μ₃
γ₁ = -------
μ₂³′²
μ₂ is the second central moment
μ₃ is the third central moment
public static populationSkewness ( array $X ) : number | ||
$X | array | list of numbers (random variable X) |
return | number |