View source: R/auxilaryfunctions.R
nb2 | R Documentation |
Since the negative binomial is not a family in base R
, an nb2()
family has been created which establishes the negative binomial as a family for use in the main rpql
function. Only the log link is available at the moment, with the variance parameterized as V = \mu + \phi\mu^2
where \phi
is the overdispersion parameter.
nb2()
Used in the form rpql(y, ..., family = nb2(), ...)
.
An object of class "family"
Francis K.C. Hui <francis.hui@gmail.com>, with contributions from Samuel Mueller <samuel.mueller@sydney.edu.au> and A.H. Welsh <Alan.Welsh@anu.edu.au>
Maintainer: Francis Hui <fhui28@gmail.com>
negative.binomial
in the MASS
package for another example of a negative.binomial family.
## Not run:
## The function is currently defined as follows
nb2 <- function () {
link <- "log"
linkfun <- function(mu) log(mu)
linkinv <- function(eta) pmax(exp(eta), .Machine$double.eps)
mu.eta <- function(eta) pmax(exp(eta), .Machine$double.eps)
variance <- function(mu, phi) mu + phi * mu^2
valideta <- function(eta) TRUE
validmu <- function(mu) all(mu > 0)
structure(list(family = "negative.binomial", link = "log",
linkfun = linkfun, linkinv = linkinv, mu.eta = mu.eta,
variance = variance, valideta = valideta, validmu = validmu,
name = link), class = "family")
}
## End(Not run)
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