Zanegbin {VGAM}R Documentation

Zero-Altered Negative Binomial Distribution

Description

Density, distribution function, quantile function and random generation for the zero-altered negative binomial distribution with parameter p0.

Usage

dzanegbin(x, p0, size, prob = NULL, munb = NULL, log = FALSE)
pzanegbin(q, p0, size, prob = NULL, munb = NULL)
qzanegbin(p, p0, size, prob = NULL, munb = NULL)
rzanegbin(n, p0, size, prob = NULL, munb = NULL)

Arguments

x, q

vector of quantiles.

p

vector of probabilities.

n

number of observations. If length(n) > 1 then the length is taken to be the number required.

size, prob, munb, log

Parameters from the ordinary negative binomial distribution (see dnbinom). Some arguments have been renamed slightly.

p0

Probability of zero, called p0. The default value of p0 = 0 corresponds to the response having a positive negative binomial distribution.

Details

The probability function of Y is 0 with probability p0, else a positive negative binomial(munb, size) distribution.

Value

dzanegbin gives the density and pzanegbin gives the distribution function, qzanegbin gives the quantile function, and rzanegbin generates random deviates.

Note

The argument p0 is recycled to the required length, and must have values which lie in the interval [0,1].

Author(s)

Thomas W. Yee

See Also

zanegbinomial, rposnegbin.

Examples

munb <- 3; size <- 4; p0 <- 0.3; x <- (-1):7
dzanegbin(x,   p0 = p0, munb = munb, size = size)
table(rzanegbin(100, p0 = p0, munb = munb, size = size))

## Not run:  x = 0:10
barplot(rbind(dzanegbin(x, p0 = p0, munb = munb, size = size),
                dnbinom(x, mu = munb, size = size)),
        beside = TRUE, col = c("blue","green"), cex.main = 0.7, las = 1,
        ylab = "Probability",names.arg = as.character(x),
        main = paste("ZANB(p0 =", p0, ", munb =", munb, ", size =", size,
                   ") [blue] vs",  " NB(mu =", munb, ", size =", size,
                   ") [green] densities", sep="")) 
## End(Not run)

[Package VGAM version 0.8-4 Index]