Kurtosis

Poisson distribution excess kurtosis.

The excess kurtosis for a Poisson random variable is

where λ is the mean parameter.

Usage

var kurtosis = require( '@stdlib/stats/base/dists/poisson/kurtosis' );

kurtosis( lambda )

Returns the excess kurtosis of a Poisson distribution with mean parameter lambda.

var v = kurtosis( 9.0 );
// returns ~0.111

v = kurtosis( 0.5 );
// returns 2.0

If provided lambda < 0, the function returns NaN.

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

Examples

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

var lambda;
var v;
var i;

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