ZINB: Zero-inflated negative binomial distribution

In extraDistr: Additional Univariate and Multivariate Distributions

Zero-inflated negative binomial distribution

Description

Probability mass function and random generation for the zero-inflated negative binomial distribution.

Usage

dzinb(x, size, prob, pi, log = FALSE)

pzinb(q, size, prob, pi, lower.tail = TRUE, log.p = FALSE)

qzinb(p, size, prob, pi, lower.tail = TRUE, log.p = FALSE)

rzinb(n, size, prob, pi)

Arguments

x, q	vector of quantiles.
size	target for number of successful trials, or dispersion parameter (the shape parameter of the gamma mixing distribution). Must be strictly positive, need not be integer.
prob	probability of success in each trial. 0 < prob <= 1.
pi	probability of extra zeros.
log, log.p	logical; if TRUE, probabilities p are given as log(p).
lower.tail	logical; if TRUE (default), probabilities are P[X \le x] otherwise, P[X > x].
p	vector of probabilities.
n	number of observations. If length(n) > 1, the length is taken to be the number required.

Details

Probability density function

f(x) = \left\{\begin{array}{ll} \pi + (1 - \pi) p^r & x = 0 \\ (1 - \pi) {x+r-1 \choose x} p^r (1-p)^x & x > 0 \\ \end{array}\right.

See Also

NegBinomial

Examples

x <- rzinb(1e5, 100, 0.6, 0.33)
xx <- -2:200
plot(prop.table(table(x)), type = "h")
lines(xx, dzinb(xx, 100, 0.6, 0.33), col = "red")

xx <- seq(0, 200, by = 0.01)
plot(ecdf(x))
lines(xx, pzinb(xx, 100, 0.6, 0.33), col = "red")

extraDistr documentation built on May 29, 2024, 9:31 a.m.