compoisson (version 0.3)

com.compute.z: Compute COM-Poisson Normalizing Constant

Description

Computes the normalizing constant in the COM-Poisson model for given values of the parameters.

Usage

com.compute.z(lambda, nu, log.error = 0.001)
	com.compute.log.z(lambda, nu, log.error = 0.001)

Arguments

lambda

Lambda value in COM-Poisson distribution

nu

Nu value in COM-Poisson distribution

log.error

Precision in the log of the normalizing constant

Value

The normalizing constant as a real number with specified precision.

Details

com.compute.z computes the COM-Poisson normalizing constant $$ z = \sum_{i=0}^\infty \frac{\lambda^j}{(j!)^\nu} $$ to the specified precision. If no precision is specified, then the package default is used.

com.compute.log.z is equivalent to log(com.compute.z(lambda, nu)) but provudes additional precision.

References

Shmueli, G., Minka, T. P., Kadane, J. B., Borle, S. and Boatwright, P., “A useful distribution for fitting discrete data: Revival of the Conway-Maxwell-Poisson distribution,” J. Royal Statist. Soc., v54, pp. 127-142, 2005.

See Also

com.fit

Examples

	data(insurance);
	fit = com.fit(Lemaire);
	z = com.compute.z(fit$lambda, fit$nu);