# cum3

##### Calculate Third Order Cumulants

Calculates an estimate of the third cumulant, or skewness, of a vector. Also, if more than one vector is specified, a product-moment of order 3 is estimated.

- Keywords
- multivariate, math

##### Usage

`cum3(a, b = a, c = a, unbiased = TRUE)`

##### Arguments

- a
A vector of observations.

- b
Another vector of observations, if not supplied it is set to the value of

`a`

. If supplied then it must be the same length as`a`

.- c
Another vector of observations, if not supplied it is set to the value of

`a`

. If supplied then it must be the same length as`a`

.- unbiased
A logical value indicating whether the unbiased estimator should be used.

##### Details

The unbiased estimator uses a multiplier of `n/((n-1)*(n-2))`

where `n`

is
the sample size, if `unbiased`

is `FALSE`

then a multiplier of `1/n`

is used.
This is multiplied by `sum((a-mean(a))*(b-mean(b))*(c-mean(c)))`

to give the
required estimate.

##### Value

The required estimate.

*Documentation reproduced from package boot, version 1.3-25, License: Unlimited*