Estimates the two parameters of the exponential Poisson distribution by maximum likelihood estimation.
exppoisson(lrate = "loglink", lshape = "loglink",
irate = 2, ishape = 1.1, zero = NULL)
An object of class "vglmff"
(see vglmff-class
).
The object is used by modelling functions such as vglm
and vgam
.
Link function for the two positive parameters.
See Links
for more choices.
Numeric.
Initial values for the shape
and rate
parameters.
Currently this function is not intelligent enough to
obtain better initial values.
See CommonVGAMffArguments
.
This VGAM family function does not work properly!
J. G. Lauder, jamesglauder@gmail.com
The exponential Poisson distribution has density function
hypergeo
package
(to use their genhypergeo
function).
The median is returned as the fitted value.
Kus, C., (2007). A new lifetime distribution. Computational Statistics and Data Analysis, 51, 4497--4509.
dexppois
,
exponential
,
poisson
.
if (FALSE) {
shape <- exp(1); rate <- exp(2)
rdata <- data.frame(y = rexppois(n = 1000, rate = rate, shape = shape))
library("hypergeo") # Required!
fit <- vglm(y ~ 1, exppoisson, data = rdata, trace = FALSE, maxit = 1200)
c(with(rdata, median(y)), head(fitted(fit), 1))
coef(fit, matrix = TRUE)
Coef(fit)
summary(fit)
}
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