Why skewness = 2* alpha/ exp(22.5) can equal the third central moment? Isn’t it skewness = third standardized moment= third central moment/ stddev^3 Here is the reference:https://en.m.wikipedia.org/wiki/Skewness In the definition of skewness. Thanks very much?
Have a look at page 12 of the Tables. The coefficient of skewness of a (translated) gamma distribution is 2 / (alpha)^0.5. Hence, the skewness = coefficient of skewness * var^3/2 = 2 / (alpha)^0.5 * (alpha^1.5) / (delta^3) = 2*alpha / (delta^3)
