VGAM (version 0.7-1)

genpoisson: Generalized Poisson distribution

Description

Estimation of the two parameters of a generalized Poisson distribution.

Usage

genpoisson(llambda = "logit", ltheta = "loge",
           ilambda = 0.5, itheta = NULL, zero = NULL)

Arguments

llambda

Parameter link function for lambda. See Links for more choices. The parameter lies in the unit interval, therefore the logit link is a reasonable default.

ltheta

Parameter link function for theta. See Links for more choices. The parameter is positive, therefore the default is the log link.

ilambda

Optional initial value for lambda.

itheta

Optional initial value for theta.

zero

An integer vector, containing the value 1 or 2. If so, lambda or theta respectively are modelled as an intercept only. The default value NULL means both linear/additive predictors are modelled as functions of t

Value

• An object of class "vglmff" (see vglmff-class). The object is used by modelling functions such as vglm, and vgam.

Details

See Consul (1989) for details.

References

Jorgensen, B. (1997) The Theory of Dispersion Models. London: Chapman & Hall

Consul, P. C. (1989) Generalized Poisson Distributions: Properties and Applications, Marcel Dekker.

See Also

poissonff.

Examples

y = rpois(n=100, lam=24)
fit  = vglm(y ~ 1, genpoisson, trace=TRUE)
fitted(fit)[1:5]
mean(y)
summary(fit)
coef(fit, matrix=TRUE)
Coef(fit)