Zabinom {VGAM} | R Documentation

## Zero-Altered Binomial Distribution

### Description

Density, distribution function, quantile function and random generation for the zero-altered binomial distribution with parameter `pobs0`.

### Usage

    dzabinom(x, size, prob, pobs0 = 0, log = FALSE)
    pzabinom(q, size, prob, pobs0 = 0)
    qzabinom(p, size, prob, pobs0 = 0)
    rzabinom(n, size, prob, pobs0 = 0)

### 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, log` | Parameters from the ordinary binomial distribution (see `dbinom`).
`pobs0` | Probability of (an observed) zero, called pobs0. The default value of `pobs0 = 0` corresponds to the response having a positive binomial distribution.

### Details

The probability function of Y is 0 with probability `pobs0`, else a positive binomial(size, prob) distribution.

### Value

`dzabinom` gives the density and `pzabinom` gives the distribution function, `qzabinom` gives the quantile function, and `rzabinom` generates random deviates.

### Note

The argument `pobs0` is recycled to the required length, and must have values which lie in the interval [0,1].

### Author(s)

T. W. Yee

### See Also

`zibinomial`, `rposbinom`.

### Examples

    size <- 10; prob <- 0.15; pobs0 <- 0.05; x <- (-1):7
    dzabinom(x, size = size, prob = prob, pobs0 = pobs0)
    table(rzabinom(100, size = size, prob = prob, pobs0 = pobs0))

    ## Not run:  x <- 0:10
    barplot(rbind(dzabinom(x, size = size, prob = prob, pobs0 = pobs0),
                    dbinom(x, size = size, prob = prob)),
            beside = TRUE, col = c("blue", "orange"), cex.main = 0.7, las = 1,
            ylab = "Probability", names.arg = as.character(x),
            main = paste("ZAB(size = ", size, ", prob = ", prob, ", pobs0 = ", pobs0,
                       ") [blue] vs",  " Binom(size = ", size, ", prob = ", prob,
                       ") [orange] densities", sep = ""))
    ## End(Not run)

[Package VGAM version 1.1-1 Index]