 |
Download a pdf copy of this help file here |
|
Download a pdf copy of this help file here |
See also: Extreme value calculations
Format: VoseSkewNormal(μ,σ,α, U)
The Skew Normal (SkewNormal) distribution is a continuous unbounded distribution developed as a deviation to the Normal distribution to allow for skewness by altering the α parameter, as illustrated in the plot below. When α=0 the distribution reduces to a Normal(μ,σ).
The SkewNormal distribution is mostly used by fitting to data that are approximately Normal but have some skewness. The SkewNormal can readily be compared to a Normal since they share the same mean μ and standard deviation σ parameters.
The range of possible skewness values lies within [-0.9952717,0.9952717]. The relationship between the parameter α and the distribution’s skewness is given in the following plot (negative α gives the equivalent negative skewness):
VoseSkewNormal generates values from this distribution or calculates a percentile. Professional and Industrial editions only.
VoseSkewNormalObject constructs a distribution object for this distribution. Professional and Industrial editions only.
VoseSkewNormalProb returns the probability density or cumulative distribution function for this distribution. Professional and Industrial editions only.
VoseSkewNormalProb10 returns the log10 of the probability density or cumulative distribution function. Professional and Industrial editions only.
VoseSkewNormalFit generates values from this distribution fitted to data, or calculates a percentile from the fitted distribution. Professional and Industrial editions only.
VoseSkewNormalFitObject constructs a distribution object of this distribution fitted to data. Professional and Industrial editions only.
VoseSkewNormalFitP returns the parameters of this distribution fitted to data. Professional and Industrial editions only.