Skewness

Poisson distribution skewness.

The skewness for a Poisson random variable is

s k e w left-parenthesis upper X right-parenthesis equals lamda Superscript negative 1 slash 2

where λ is the mean parameter.

Usage

var skewness = require( '@stdlib/math/base/dists/poisson/skewness' );

skewness( lambda )

Returns the skewness of a Poisson distribution with mean parameter lambda.

var v = skewness( 9.0 );
// returns ~0.333

v = skewness( 0.5 );
// returns ~1.414

If provided lambda <= 0, the function returns NaN.

var v = skewness( -1.0 );
// returns NaN

Examples

var randu = require( '@stdlib/random/base/randu' );
var round = require( '@stdlib/math/base/special/round' );
var skewness = require( '@stdlib/math/base/dists/poisson/skewness' );

var lambda;
var v;
var i;

for ( i = 0; i < 10; i++ ) {
    lambda = randu() * 20.0;
    v = skewness( lambda );
    console.log( 'λ: %d, skew(X;λ): %d', lambda.toFixed( 4 ), v.toFixed( 4 ) );
}