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@wikipedia


A set of statistical metrics, characterizing the average deviation of a given numerical the numerical values in the given dataset

LaTeX Math Inline
body--uriencoded--x = \%7B x_1, \, x_2, \, x_3 , ... x_N \%7D
 from its Mean Value 
LaTeX Math Inline
body\mu(x)
 :

LaTeX Math Block
alignmentleft
\bar \mu_n = \frac{\mu_n}{\sigma^n}, E[ ( x - \mu)^n ] = \frac{1}{N} \sum_{i=1}^N (x_i - \mu)^n\ \ n \geq 3

where 

LaTeX Math Inline
body

N

\mu_n

n-

LaTeX Math Inline
bodyE
LaTeX Math Inline
bodyn

LaTeX Math Inline
body\sigma


The common assumption is that zero-th central momentum is unit-value: concept makes sense only for the central momentums of higher oder than 

LaTeX Math Inline
bodyn \geq 3
, since lower order central momentums  
LaTeX Math Inline
body\bar \mu_0 \equiv 1/\sigma
.By definition the first central momentum is always zero: ,
LaTeX Math Inline
body\bar \mu_1 \equiv 0
.The second central momentum (μ2) is also called variance ,
LaTeX Math Inline
body--uriencoded--\bar \mu_2 = \sigma%5e2
, where 
LaTeX Math Inline
body\sigma
 is standard deviation.
equiv 1
 are trivial and do not carry additional information on dataset distribution.

The most popular application is the 3-rd order standardized central momentum The third central momentum is characterizing asymmetry of the variance 

LaTeX Math Inline
body--uriencoded--\mu_3 = \bar \mu_3 \cdot \sigma%5e3
, where 
LaTeX Math Inline
body\bar \mu_3
 is skewnesswhich is called skewness and characterizes asymmetry of the dataset distribution.


See also

...

Formal science / Mathematics / Statistics / Statistical Metric Natural Science /  System / Model Central momentum