skewness
Returns the skewness of this binomial distribution.
Measures the asymmetry of the distribution. When the success probability is below 0.5 the distribution is right-skewed; when above 0.5, left-skewed; at exactly 0.5 the distribution is symmetric and the skewness is zero. Returns Double.NaN for degenerate cases (zero trials, or probability of 0 or 1).
Return
the skewness, or Double.NaN for degenerate cases.