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
    (ii = 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"),
            main=paste("ZANB(p0=", p0, ", munb=", munb, ", size=", size, ") (blue) vs",
                            " NB(mu=", munb, ", size=", size, ") (green)", sep=""),
            names.arg = as.character(x), cex.main=0.7, las=1)
    ## End(Not run)

[Package VGAM version 0.7-9 Index]