This is a pretty complicated formula that basically looks at how flat or peaked a set of scores is. You can see that if each score is the same, then the numerator is zero and K = 0, indicating no skewness. K equals zero when the distribution is normal or mesokurtic (now there’s a new word to throw around). If the individual scores (the Xs in the formula) differ greatly from the mean (and there is lots of variability), then the curve will probably be quite flat.
