ZINB() R function from [extraDistr]

Zero-inflated negative binomial distribution

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


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.f(x) = [if x = 0:] (1-\pi)+\pi * p^r [else:] (1-\pi) * dnbinom(x, size, prob)

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")

ZINB function

Zero-inflated negative binomial distribution

Arguments

Details

Examples

See Also