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However, a symmetric unimodal or multimodal distribution always has zero skewness. Example of an asymmetric distribution with zero skewness. This figure serves as a counterexample that zero skewness does not imply symmetric distribution necessarily. (Skewness was calculated by Pearson's moment coefficient of skewness.)
Thus, a d-variate distribution is defined to be mirror symmetric when its chiral index is null. The distribution can be discrete or continuous, and the existence of a density is not required, but the inertia must be finite and non null. In the univariate case, this index was proposed as a non parametric test of symmetry. [2]
The Asymmetric Laplace distribution is commonly used with an alternative parameterization for performing quantile regression in a Bayesian inference context. [4] Under this approach, the κ {\displaystyle \kappa } parameter describing asymmetry is replaced with a p {\displaystyle p} parameter indicating the percentile or quantile desired.
The expectile distribution, which nests the Gaussian distribution in the symmetric case. The Fisher–Tippett, extreme value, or log-Weibull distribution; Fisher's z-distribution; The skewed generalized t distribution; The gamma-difference distribution, which is the distribution of the difference of independent gamma random variables.
The asymmetric generalized normal distribution can be used to model values that may be normally distributed, or that may be either right-skewed or left-skewed relative to the normal distribution. The skew normal distribution is another distribution that is useful for modeling deviations from normality due to skew.
The shape of a distribution will fall somewhere in a continuum where a flat distribution might be considered central and where types of departure from this include: mounded (or unimodal), U-shaped, J-shaped, reverse-J shaped and multi-modal. [1] A bimodal distribution would have two high points rather than one. The shape of a distribution is ...
Asymmetry is the absence of, or a violation of, symmetry (the property of an object being invariant to a transformation, such as reflection). [1] Symmetry is an important property of both physical and abstract systems and it may be displayed in precise terms or in more aesthetic terms. [2]
Unlike metrics, divergences are not required to be symmetric, and the asymmetry is important in applications. [3] Accordingly, one often refers asymmetrically to the divergence "of q from p" or "from p to q", rather than "between p and q".