rnegbin {MASS}  R Documentation 
Function to generate random outcomes from a Negative Binomial distribution,
with mean mu
and variance mu + mu^2/theta
.
rnegbin(n, mu = n, theta = stop("'theta' must be specified"))
n 
If a scalar, the number of sample values required. If a vector,
length(n) is the number required and n is used as the mean vector if
mu is not specified.

mu 
The vector of means. Short vectors are recycled. 
theta 
Vector of values of the theta parameter. Short vectors are recycled.

The function uses the representation of the Negative Binomial distribution
as a continuous mixture of Poisson distributions with Gamma distributed means.
Unlike rnbinom
the index can be arbitrary.
Vector of random Negative Binomial variate values.
Changes .Random.seed
in the usual way.
# Negative Binomials with means fitted(fm) and theta = 4.5 fm < glm.nb(Days ~ ., data = quine) dummy < rnegbin(fitted(fm), theta = 4.5)