skewness A measure of asymmetry in frequency distributions. The skew in a distribution is the degree to which frequencies trail towards extreme scores in one direction away from the majority of cases. Negative skew means cases trail to the left and positive skew involves trailing to the right. It is important to know the shape of a distribution in order to know what measures (for example of central tendency) can best describe it.

skewness An expression of the degree of asymmetry shown on a frequency distribution. A non-skewed distribution is a perfect, normal(Gaussian) distribution. Grainsize distributions are skewed positively where larger particles are more numerous than fine ones, or negatively where finer particles exceed coarse within the distribution.