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  2. Skewness - Wikipedia

    en.wikipedia.org/wiki/Skewness

    Example distribution with positive skewness. These data are from experiments on wheat grass growth. In probability theory and statistics, skewness is a measure of the asymmetry of the probability distribution of a real-valued random variable about its mean. The skewness value can be positive, zero, negative, or undefined.

  3. D'Agostino's K-squared test - Wikipedia

    en.wikipedia.org/wiki/D'Agostino's_K-squared_test

    In the following, { x i } denotes a sample of n observations, g 1 and g 2 are the sample skewness and kurtosis, m j ’s are the j-th sample central moments, and ¯ is the sample mean. Frequently in the literature related to normality testing, the skewness and kurtosis are denoted as √ β 1 and β 2 respectively.

  4. L-moment - Wikipedia

    en.wikipedia.org/wiki/L-moment

    A quantity analogous to the coefficient of variation, but based on L-moments, can also be defined: = / , which is called the "coefficient of L-variation", or "L-CV". For a non-negative random variable, this lies in the interval ( 0, 1 ) [1] and is identical to the Gini coefficient.

  5. Beta distribution - Wikipedia

    en.wikipedia.org/wiki/Beta_distribution

    The accompanying plot of skewness as a function of variance and mean shows that maximum variance (1/4) is coupled with zero skewness and the symmetry condition (μ = 1/2), and that maximum skewness (positive or negative infinity) occurs when the mean is located at one end or the other, so that the "mass" of the probability distribution is ...

  6. Shape parameter - Wikipedia

    en.wikipedia.org/wiki/Shape_parameter

    In probability theory and statistics, a shape parameter (also known as form parameter) [1] is a kind of numerical parameter of a parametric family of probability distributions [2] that is neither a location parameter nor a scale parameter (nor a function of these, such as a rate parameter).

  7. Nonparametric skew - Wikipedia

    en.wikipedia.org/wiki/Nonparametric_skew

    The nonparametric skew is one third of the Pearson 2 skewness coefficient and lies between −1 and +1 for any distribution. [5] [6] This range is implied by the fact that the mean lies within one standard deviation of any median. [7] Under an affine transformation of the variable (X), the value of S does not change except for a possible change ...

  8. Skewed generalized t distribution - Wikipedia

    en.wikipedia.org/wiki/Skewed_generalized_t...

    where is the beta function, is the location parameter, > is the scale parameter, < < is the skewness parameter, and > and > are the parameters that control the kurtosis. and are not parameters, but functions of the other parameters that are used here to scale or shift the distribution appropriately to match the various parameterizations of this distribution.

  9. Skew normal distribution - Wikipedia

    en.wikipedia.org/wiki/Skew_normal_distribution

    The exponentially modified normal distribution is another 3-parameter distribution that is a generalization of the normal distribution to skewed cases. The skew normal still has a normal-like tail in the direction of the skew, with a shorter tail in the other direction; that is, its density is asymptotically proportional to for some positive .